CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to and is a continuation-in-part of now published U.S. patent application Ser. No. 10/005,609 filed Nov. 7, 2001, which is itself related to and claims priority to U.S. Provisional Patent Application Ser. No. 60/249,796 filed Nov. 17, 2000 and U.S. Provisional Patent Application Ser. No. 60/288,310 filed May 2, 2001, with the disclosure of said two provisional patent applications hereby incorporated by reference in their entireties herein. Priority is hereby also claimed to U.S. Provisional Application Ser. Nos. 60/249,796 and 60/288,310.  
         [0002]     This application is also related to U.S. Provisional Application Nos. 60/540,392 and 60/540,678 filed Jan. 30, 2004, and claims priority to both said provisional applications, and the disclosures of both applications are also specifically incorporated by reference herein. 
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0003]     This invention pertains to the field of global electronic trading of commodities and financial instruments. In a more specific aspect, this invention relates to the concept of Proximity Measures, which coupled with a network-dealing architecture may represent the limit point of convergence of the sequence of evolution of methods dealing with online transaction of items between parties.  
       BACKGROUND OF THE INVENTION  
       [0004]     There has previously been described a method of online exchange of any pairs of instruments between any set of parties in the absence of a centralised exchange mechanism, but in the presence of a network of implicit credit relationships between them.  
         [0005]     Such a Decentralised Network Dealing architecture is disclosed in published U.S. application Ser. No. 10/005,609, filed Nov. 7, 2001 and published Jul. 11, 2002 as Pub. No. US. 2002/0091624 A1. In this regard, it will be appreciated that the invention disclosed herein may be implemented through an architecture such as that described in said application Ser. No. 10/005,609, the disclosure of which is specifically incorporated by reference herein. Of course, as will be readily apparent to those of ordinarily skill in the art, modifications may be made to such an architecture, or an alternative architecture providing similar functionality sufficient to implement the invention may be employed in place thereof.  
       BACKGROUND ART  
       [0006]     Wright, Ben, “Unlocking the C2C forex riddle”, euromoney.com, Jul. 25, 2001, U.K., provides a general discussion of some of the business aspects implemented through the system and method described in U.S. application Ser. No. 10/005,609.  
         [0007]     Morris, Jennifer, “Forex goes into future shock”, Euromoney, October 2001, gives a general description of several computerized foreign exchange platforms, including one described in the present patent application.  
         [0008]     Ahuja, R. K., Magnanti, T. L., and Orlin, J. B., Network Flows; Theory, Algorithms, and Applications, Chapters 7 and 9 (Prentice-Hall, Inc. 1993), U.S.A., sets forth some algorithms that may be useful in implementing the present invention.  
         [0009]     U.S. Pat. No. 5,375,055 discloses a relatively simple trading system that is capable of implementing only single-hop trades. On the other hand, the present invention can accommodate multi-hop trades. Further, in U.S. Pat. No. 5,375,055, the user is given information that suggests to him that he can take a trade when he may not have enough credit to take the whole trade. In the present invention, on the other hand, if only part of a trade can be executed, that information is given to the user; the user knows that he has enough credit to execute at least the best bid and best offer that are displayed on his computer.  
         [0010]     An even simpler trading system is disclosed in European patent application 0 411 748 A2 and in granted European patents 0 399 850 B1 and 0 407 026 B1, all three of which are assigned to Reuters Limited. These Reuters documents describe a system in which information concerning a potential trade is displayed even if the user can&#39;t execute it at all. In the present invention, such a potential trade would not be displayed at all. Furthermore, the only credit limits that can be accommodated in the Reuters system are volume limits for the purposes of limiting settlement risk. In the present invention, any agent may set credit limits in multiple ways so as to limit not only settlement risk (measured both by individual instrument volumes and by notional absolute values) but also exposure risk. Furthermore, the Reuters keystations require a human operator. In the present invention, on the other hand, an API (application programming interface) enables any participant to develop programs which partially or fully automate the trading process.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     Methods, systems, and computer readable media for facilitating trading two items (L,Q) from the group of items comprising commodities and financial instruments. At least two agents ( 2 ) want to trade some instrument L at some price quoted in terms of another instrument Q. The exchange of L and Q is itself a financial instrument, which is referred to as a traded instrument. A trading channel ( 3 ) between the two agents ( 2 ) allows for the execution of trades. Associated with each channel ( 3 ) are trading limits configured by the two agents ( 2 ) in order to limit risk. A central computer ( 1 ) coupled to the two agents ( 2 ) is adapted to convey to each agent ( 2 ) current tradable prices and available volumes for the exchange of L for Q and for the exchange of Q for L, taking into account the channel ( 3 ) trading limits. The central computer ( 1 ) facilitates trades that occur across a single trading channel ( 3 ) and trades that require the utilization of multiple trading channels ( 3 ).  
         [0012]     In a yet further aspect as disclosed herein, this invention provides in a method and system implemented through a network, that an entity, for example, a buyer, may set rules as to types of information it may receive from another entity, e.g., a seller, and vice versa. The information includes among other things, the types of goods that can be traded. Thus, a party A may set rules for a party B, who then sets rules for party C, which in turn carries forward the information from party A to party C through its own rules that it sets. Ultimately, trading between A and C is facilitated for goods at prices and up to amounts that A, B, and C have set and modified along the way.  
         [0013]     In a more specific aspect, a method of conducting trading includes transmitting a request from one party about an item the party is willing to trade, specifying rules about what will be acceptable. Responses are received from other parties concerning requests which are responsive to the rules. A trade is conducted with one or more of the parties responding in accordance with the rules.  
         [0014]     In an alternative aspect, the method involves a first party defining rules it deems define specific properties of an item and relaying to any other party the information. A second party may view the information and respond, or relay information, setting its own rules, to one or more other parties. Replies are transmitted to the first party in response to the rules set by the first party. The replies are sorted by the likelihood of being accepted.  
         [0015]     In a further aspect, the invention relates to a system of interconnected network computers configured for conducting the afore-mentioned methods.  
         [0016]     In a yet still further aspect, the invention relates to an apparatus for facilitating trading two items. The apparatus includes at least one agent offering to trade an item. A trading channel is provided between the at least one agent to another agent allowing for execution of trades. Flow limits are set on the traded items and on any underlying instruments to be exchanged on settlement of the traded items. A central computer is coupled to the at least one agent. The computer is adapted to convey to other agents individualized current tradable proximity to bid, properties of items and sizes to a depth. The proximity to bid, properties of items, sizes and depth automatically determine buyer taking into account all of the limits imposed by the at least one agent. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     Having this generally described the invention, it will become better understood from the following specification, reference being had to the accompanying drawings, in which:  
         [0018]      FIG. 1  is a block diagram illustrating a “type zero” trading system embodiment of the present invention.  
         [0019]      FIG. 2  is a block diagram illustrating a “type 1” trading system embodiment of the present invention.  
         [0020]     There is no  FIG. 3 .  
         [0021]      FIG. 4  is a block diagram illustrating a “type 2” trading system embodiment of the present invention.  
         [0022]      FIG. 5  is a block diagram illustrating a “type 2” back-to-back trade using the present invention.  
         [0023]      FIG. 6  is a block diagram illustrating an interlocking network of type 1 and type 2 atomic units.  
         [0024]      FIG. 7  is a schematic diagram illustrating trading limits for a traded instrument being traded between four agents  4 , 5  using three trading channels  3 .  
         [0025]      FIG. 8  is a block diagram illustrating various ways that agents  2  can be connected to enable them to use the present invention.  
         [0026]      FIG. 9  is a timeline illustrating an embodiment of the matching process used in the present invention.  
         [0027]      FIG. 10  is a block diagram illustrating an embodiment of the border outpost process of the present invention.  
         [0028]      FIG. 11  is a deal fulfillment graph.  
         [0029]      FIG. 12  is a flow diagram illustrating the sequence of screen shots appearing on the computer of an agent  2  using the present invention.  
         [0030]      FIG. 13  illustrates a log-in screen  21  of the computer of an agent  2 .  
         [0031]      FIG. 14  illustrates a custom limit order book overview window  24  (multiple traded instruments).  
         [0032]      FIG. 15  illustrates a custom limit order book window  25  (single traded instrument).  
         [0033]      FIG. 16  illustrates a net exposure monitor  35 .  
         [0034]      FIG. 17  illustrates a balance sheet window  36 .  
         [0035]      FIG. 18  illustrates an open order overview and management window  33 .  
         [0036]      FIG. 19  illustrates a bid creation dialog box  28 .  
         [0037]      FIG. 20  illustrates an offer creation dialog box  29 .  
         [0038]      FIG. 21  illustrates a buy (immediate execution bid) dialog box  30 .  
         [0039]      FIG. 22  illustrates a sell (immediate execution offer) dialog box  31 .  
         [0040]      FIG. 23  is a flow diagram illustrating the computation of a custom limit order book  24 , 25 .  
         [0041]      FIG. 24  is a flow diagram illustrating the computation of multi-hop flow limits for a single traded instrument among all accounts.  
         [0042]      FIG. 25  is a flow diagram illustrating computation of a directed graph of single-hop flow limits for a single traded instrument among all accounts.  
         [0043]      FIG. 26  is a flow diagram illustrating computation, of minimum and maximum excursions for a single account A and a single traded instrument.  
         [0044]      FIG. 27  is a flow diagram illustrating computation of a position limit for a lot instrument L.  
         [0045]      FIG. 28  is a flow diagram illustrating computation of a position limit for a quoted instrument Q.  
         [0046]      FIG. 29  is a flow diagram illustrating computation of a volume limit for a lot instrument L.  
         [0047]      FIG. 30  is a flow diagram illustrating computation of a volume limit for a quoted instrument Q.  
         [0048]      FIG. 31  is a flow diagram illustrating computation of a notional position limit.  
         [0049]      FIG. 32  is a flow diagram illustrating computation of a notional volume limit.  
         [0050]      FIG. 33  is a flow diagram illustrating computation of a traded instrument L:Q position limit.  
         [0051]      FIG. 34  is a flow diagram illustrating computation of a traded instrument L:Q volume limit.  
         [0052]      FIG. 35  is a flow diagram illustrating reporting by computer  1  of a single-hop trade.  
         [0053]      FIG. 36  is a flow diagram illustrating reporting by computer  1  of a multi-hop trade. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0054]     The present invention enables an arbitrary number of agents  2  of arbitrary type (such as corporate treasuries, hedge funds, mutual funds and other collective investment schemes, banks and other financial institutions, and other institutions or persons) to trade commodities and financial instrument pairs directly amongst each other (thus facilitating client-to-client, or C2C trading) by making orders to their peers to buy and sell the traded instrument pairs over “credit atomic units” and “credit molecules”.  
         [0055]     By way of example, the application highlighted most often herein is the spot foreign exchange (spot FX) market, but it must be understood that the present invention has applicability to trading in any type of over-the-counter commodity or financial instrument, including physical commodities, energy products (oil, gas, electricity), insurance and reinsurance products, debt instruments, other foreign exchange products (swaps), and compound instruments and other derivatives composed or derived from these instruments.  
         [0056]     A trade is the exchange of a lot of instrument L for a quoted instrument Q. The lot instrument L is traded in an integral multiple of a fixed quantity refered to as the lot size. The quoted instrument Q is traded in a quantity determined by the quantity of the lot instrument L and the price. The price is expressed as Q per L. In a spot FX trade, the lot instrument L and the quoted instrument Q are implicit contracts for delivery of a currency on the “spot” date (typically two business days after the trade date).  
         [0057]     In the present specification and claims, entities that wish to trade with each other are referred to as “agents”  2 . Agents  2  that extend credit to other agents  2  are referred to as credit-extending agents  5 . Agents  2  that do not extend credit to other agents  2  are referred to as clients  4  or non-credit-extending agents  4 .  
         [0058]     Two agents  2  may have direct trading channels  3  between them, where the trading channels  3  correspond to credit extended from one credit-extending agent  5  (typically a bank, financial institution, or any clearing entity) to the other agent  2 . Trading channels  3  are typically secured via placement of collateral (margin) or other form of trust by an agent  2  with the credit-extending agent  5 . Typically, trading channels  3  amongst credit-extending agents  5  and non-credit-extending agents  4  already exist. In the spot FX market, these trading channels  3  are refered to as trading accounts. In the case that two credit-extending agents  5  have a trading channel  3  between them, only one agent  2  acts in a credit-extending capacity with regards to that trading channel  3 .  
         [0059]     Credit-extending agents  5  that allow the central computer  1  to utilize a portion of their trading channels  3  to allow other agents  2  to trade with each other are refered to as “credit-bridging agents”  5 . In a preferred implementation of the present system, existing banks, financial institutions, and clearing entities are credit-bridging agents  5  as well as credit-extending agents  5 ; and existing trading customers of those institutions  5  are clients  4 .  
         [0060]     Compared with prior art systems, the present invention gives a relative advantage to clients  4  compared to credit-extending agents  5 , by enabling one-way or two-way orders from any agent  2  to be instantly displayed to all subscribing agents  2 , enabling a trade to take place at a better price, with high likelihood, than the price available to clients  4  under prior art systems. The present invention brings together clients  4  who may be naturally on opposing sides of a trade, without conventional spreads historically charged to them  4  by credit-extending agents  5  for their  5  service as middlemen. Of course, credit-extending agents  5  also benefit on occasions when they are natural sellers or buyers.  
         [0061]     Unlike prior art systems, the present invention arranges multi-hop deals to match orders between natural buyers and sellers who need not have a direct trading relationship. For the application to spot FX trading, a multi-hop deal can be realized through real or virtual back-to-back trades by one or more credit-bridging agents  5 . In terms of the underlying transfers of financial instruments, a multi-hop deal is similar to the existing practice of trade “give-ups” from one broker to another.  
         [0062]     Unlike prior art systems, the present invention computes trading limits from not only cumulative volume but also from net position limits, where both volume and position limits may be set in terms of the traded instrument (instrument L for instrument Q), in terms of any underlying instruments to be exchanged (delivered) upon settlement (such as L individually, Q individually, or other instruments), or in terms of the notional valuations of such instruments. This allows all agents  2 , especially credit-bridging agents  5 , to control risk far more flexibly. Limiting traded or delivered instruments&#39; cumulative volume helps to manage settlement risk. Limiting a traded instrument&#39;s net position (net L:Q position) helps to manage market risk. Limiting a delivered underlying instrument&#39;s net position (total net L, total net Q, or some other underlying instrument&#39;s position) helps manage market and credit risk by reflecting the ultimate effect of any trade on any account&#39;s future balance sheet. The cumulative volume limits allowed by prior art systems are able to address only settlement risk concerns.  
         [0063]     The present invention has a natural symmetry; in the preferred implementation, not only are credit-bridging agents  5  (financial institutions) able to operate as market makers and post one-way Oust a bid or ask) and two-way (both bid and ask) prices to agents  2 , but clients  4  may post one-way and two-way prices to credit-bridging agents  5  and other clients  4  of any other credit extending or credit bridging agent  5 . This symmetry is not present in prior art trading systems.  
         [0064]     The present invention uses a central computer  1  to calculate trading limits, to prepare custom limit order books  24 , 25 , and to match orders, but all post-trade bookkeeping and settlement is handled in a de-centralized manner by the counterparties  2  involved in each trade. The central computer  1  is a network of at least one physical computer acting in a closely coordinated fashion.  
         [0065]     Every agent  2  subscribing to a system employing the present invention can be thought of as a node  2  in an undirected graph ( FIGS. 1-6 ,  11 ). The undirected edges  3  of such graphs indicate the existence of a trading channel  3  (account) between two nodes  2 , typically an arrangement of trading privileges and limits based on the extension of credit from one node  2  to another  2  and likely backed by collateral placed by one node  2  with the other  2 . Some nodes  5  in the graph, corresponding to credit-bridging agents  5 , allow credit to be bridged, while other nodes  4  are clients  4  who permanently or temporarily forbid credit bridging. For the application to spot FX trading, a credit-bridging agent  5  authorizes the central computer  1  to initiate back-to-back spot trades, where simultaneous trades in opposite directions at the same price are made between the credit bridging agent  5  and two or more different agents  2 , such that the net position effect to the credit bridging agent  5  is exactly zero.  
         [0066]     For each trading channel (account  3 ), the central computer  1  maintains a set of limits set by the credit-extending agent  5  and a set of limits set by the non-credit-extending agent  2 . Either of these sets of limits may be empty. These limits specify maximums of cumulative volume of each traded instrument L:Q, maximum cumulative volume of an underlying instrument (e.g. L, Q, or other), maximum cumulative notional value (e.g. U.S. dollar equivalent), maximum positive or negative net position of each traded instrument L:Q, maximum positive or negative net position of the underlying instrument (e.g. L, Q, or other), and maximum absolute net position notional (e.g., U.S. dollar equivalent) value total.  
         [0067]     For each trading channel (account)  3 , the central computer  1  maintains information sufficient to compute the current value of all the quantities upon which limits may be placed. The cumulative volume values are reset to zero with some period, typically one business day, at such a time as is agreeable to both agents. It is illustrative to note that the cumulative volume values always increase toward their limit with each trade, while the net position values may be decreased back to zero or near zero and may change in sign.  
         [0068]     An agent  2  may add, remove, or adjust any of the elements of the set of limits specified by that agent  2  at any time.  
         [0069]     Since trading is permitted or denied based on these limit-related values, the central computer  1  provides a way for the agents  2  that are parties to an account to inform the central computer  1  of any external activity that would affect these values, such as odd-lot trades and trades made through existing trading devices, or to simply reset all limit-related values to a predefined state.  
         [0070]     Based on the current values of all these limit-related quantities, the central computer  1  computes for each traded instrument L:Q a directed graph ( FIG. 7 ) of maximum excursions. In the directed graph for each traded instrument L:Q, each directed edge  3  from a node  2  to another node  2  has a value that indicates, based on the current position, how many of the traded instrument L:Q may be bought by the first node  2  from the second node  2 . There are typically directed edges  3  in both directions between any pair of nodes  2 , since the instrument L:Q may be bought or sold. The trading limit values (maximum excursions) of these buying and selling edges  3  between two nodes  2  vary from moment to moment as trades are made and/or credit limits are adjusted by either node  2 .  
         [0071]     For all traded instruments L:Q and for all nodes  2  that trade L:Q and for all other nodes  2  that trade L:Q, the central computer  1  uses the directed graph of maximum excursions ( FIG. 7 ) to compute the maximum flow from the first node  2  to the second node  2 . Note that this means that each pair of nodes  2  that trade L:Q will have the maximum flow between them  2  calculated in both directions.  
         [0072]     The prior art systems could be simulated by the present invention by first eliminating the ability of any node  2  to be a credit-bridging agent  5  so that the “single-pair maximum flow” is merely the flow enabled by directed edges  3  connecting the pair of nodes  2  directly. Second, all trading limits by non-credit-extending agents  4  would be disabled and only cumulative volume limits on underlying instruments would be allowed for credit-extending agents  5 , corresponding to limits only on settlement risk.  
         [0073]     For purposes of illustrating the present invention, consider, for example, an agent A extending credit to agent B for the purposes of trading spot FX using the present invention, and between the U.S. dollar (USD), Euro (EUR), and Japanese Yen (JPY) in particular. Suppose agent B buys 1 lot of EUR:USD at 0.9250, then sells 1 lot of EUR:JPY at 110.25, with both trades having agent A as counterparty  2 . The first trade will upon settlement result in 1,000,000 EUR received by agent B and 925,000 USD paid by agent B, while the second trade will result in 1,000,000 EUR paid by agent B and  110 , 250 , 000  JPY received by agent B. From the perspective of agent B, the account stands +1M EUR toward the EUR:USD cumulative volume limit, +1M EUR toward the EUR:USD net position limit, +1M EUR toward the EUR:JPY cumulative volume limit, −1M EUR toward the EUR:JPY net position limit, +2M EUR toward the EUR cumulative volume limit, +925,000 USD toward the USD cumulative volume limit, +110,250,000 JPY toward the JPY cumulative volume limit, ZERO with respect to the EUR net position limit, −925,000 USD toward the USD net position limit, and +110,250,000 JPY toward the JPY net position limit. Further supposing that the instrument valuations in agent B&#39;s home currency of USD are 0.9200 EUR:USD and 0.009090 JPY:USD, then the account stands (2M×0.9200+925,000+110,250,000×0.009090=) 3,767,172.50 USD toward the notional USD cumulative volume limit (useful for limiting settlement risk), and (0×0.9200+925,000+110,250,000×0.009090=) 1,927,172.34 USD toward the absolute notional net position total.  
         [0074]     Now suppose agent B buys 1 lot of USD:JPY at 121.50, which upon settlement will result in 1,000,000 USD received and 121,500,000 JPY paid. The net single-instrument positions are now 0 EUR, 75,000 USD, and −10,250,000 JPY. Rather than delivering JPY at settlement (which will entail carrying a JPY debit balance in the account), agent B will probably choose to arrange an odd-lot deal with agent A to buy 10,250,000 JPY at a rate of, for instance, 121.40 USD:JPY, at a cost of 84,431.63 USD, resulting in final account position values of 0 EUR, −9,431.63 USD, and 0 JPY. In other words, agent B has lost 9,431.63 USD in its account with agent A once all the settlements occur.  
         [0075]     Alternatively, agent B may choose to “roll forward” any EUR or JPY net position from the spot date to the next value date, or to any forward date by buying or selling an appropriate FX swap instrument from or to agent A.  
         [0076]     Odd-lot spot, odd-lot forward, odd-lot swap, and deals with a specific counterparty  2  are not amenable to trading via the “limit-order book” matching system, but instead may be facilitated by the central computer  1  through a request-for-quote mechanism. Since the central computer  1  knows the net positions of all the accounts, it may further recommend such deals on a periodic basis, such as a particular time that both agents  2  consider to be the end of the business day for the account in question.  
         [0077]     For the application of the present invention to markets other than spot FX, triangular interactions between traded instrument pairs are not as much a concern. The limits set by credit-extending agents  5  are handled the same way, where the limits on commodity holdings or currency payments are translated by the central computer  1  into excursion limits (how many lots an agent  2  may buy or sell) in real-time.  
         [0078]     The present invention can be implemented in a combination of hardware, firmware, and/or software. The software can be written in any computer language, such as C, C++, Java, etc., or in a combination of computer languages. The hardware, firmware, and software provide three levels of content: a) trade screens, b) post-trade content for back offices and clearing units, and c) real-time credit management content. Through an API (application programming interface)  38 , agents  2  can securely monitor and change in real time the credit limits they have specified for each trading channel  3  in which they participate. (Note that the maximum flow across a trading channel  3  is the minimum of the trading limits specified by the two agents  2  associated with the channel  3 , so a non-credit-extending agent  4  can only further reduce the credit limits assigned by the credit-extending agent  5 .)  
         [0079]     The link between the agents  2  and the central computer  1  can be any telecommunications link—wired, wireless, Internet, private, etc. Computer  1  can be located anywhere in the world. It can be mirrored for purposes of data backup, to increase throughput, or for other reasons; in that case, there is a second central computer  1 ( 2 ). The backup central computer  1 ( 2 ) is a network of at least one physical computer operating in a closely coordinated fashion. Such a backup computer  1 ( 2 ) is shown in  FIG. 8 , and insures that there will be no interruption of service with hardware, software, or network  6 , 7  failures (neither during the failure nor during the needed repairs); and further insures that the present invention has the ability to recover from a disaster event.  
         [0080]     Since the present invention operates on a global scale, said operation has to satisfy local laws and regulations to enable the services of the present invention to be provided. The present invention is therefore designed to enable such accommodations to be made.  
         [0081]     The present invention supports purpose-specific “atomic units” enabling trading between specific types of agents  2 . The basic atomic units are “type 0”, “type 1”, and “type 2”, where a “type 0 unit” involves a single pair of agents  2  where one extends credit to the other, a “type 1 unit” involves a single client  4  trading with a collection of credit-extending agents  5 , and a “type 2 unit” involves a single credit-bridging agent  5  enabling a collection of its clients  4  to trade with itself  5  and with each other  4 .  
         [0082]      FIG. 1  illustrates the simplest atomic unit, type 0. A first agent  2 ( 1 ) and a second agent  2 ( 2 ) wish to trade at any given time some number of round lots of instrument L in exchange for a quantity of another item Q, which we refer to as the quoted instrument or quoted currency. A trading channel  3  (account) between the two agents  2  allows for the execution of the trades and settlement of the underlying instruments. Inherent in the trading channel  3  are flow limits (trading limits) on the items L,Q being traded and limits on any underlying instruments exchanged upon settlement of the L,Q trade. A central computer  1 , under control of the operator or owner of the system, is coupled to the two agents  2 . The computer  1  is adapted to convey to each agent  2  current bid orders and offer orders originating from the other participating agent  2 . The current set of tradable bid and offered prices and sizes is constrained by the trading channel&#39;s trading limits, and is preferably conveyed in the form of a custom limit order book  24 , 25  for each agent  2 , as will be more fully described below. The custom limit order book  24 ,  25  is a chart, typically displayed on the agent&#39;s computer, of a preselected number of bids and offers for the instrument pair L,Q in order of price, and within price, by date and time (oldest first).  
         [0083]     Typically, but not necessarily, each agent  2  is coupled to the central computer  1  when the agents  2  are trading. The identification of one of the two agents  2  as the “credit-extending agent  5 ” is necessary only for the creation of a trading channel  3 , since either agent  2  may post orders (making the market) in the same way.  
         [0084]      FIG. 2  illustrates the type 1 atomic unit: a client agent  4  is looking to trade with several credit-extending agents  5  with whom it  4  has a credit relationship. Note that because each credit-extending agent  5  participates in only a single trading channel  3  (with which the central computer  1  is aware), there is no opportunity for the credit-extending agents  5  to act as credit-bridigng agents  5 . The type 1 scenario involves the client  4  placing a one-way or a two-way order via computer  1 . Computer  1  insures that every institution  5  with which the client  4  has a credit relationship sees the order instantaneously. If none of the institutions  5  wish to deal at the client&#39;s current price, they  5  may post their own counter-offers that then appear on the client&#39;s custom limit order book  24 , 25 , but not on those of the other institutions  5 . The client  4  may then choose to modify or cancel its  4  order to deal at the best price possible, while the institutions  5  benefit by seeing this client&#39;s  4  possible interest in buying or selling.  
         [0085]     The institutions  5  may also supply via computer  1  tradable bid and offered prices to the client  4  that will not be seen by the other institutions  5 .  
         [0086]     The solid lines in  FIG. 2  represent credit relationships between client  4  and credit-extending agents  5 . The credit-extending agents  5  may have credit relationships outside the scope of the present invention, but only those trading channels  3  whose credit limits are maintained by the central computer  1  are illustrated or discussed. The dashed lines in  FIG. 2  represent communication links between the agents ( 4 , 5 ) and the central computer  1 .  
         [0087]     As a sub-species of type 1, there can be multiple clients  4 , as long as all such clients  4  have credit relationships with the same credit-extending agents  5 , and the clients  4  are not allowed to trade with each other  4 .  
         [0088]     Computer  1  provides several post-trade capabilities to the client  4  and to the financial institution&#39;s  5  trading desk as well as to its  5  back office and credit desk, all in real-time.  
         [0089]     The clearing of the trade is done by conventional means. The operator of computer  1 , though it could, does not need to act as a clearing agent and does not need to hold as collateral or in trust any financial or other instruments. The client  4  can direct that all clearing is to be handled by a certain credit-extending agent  5 . The clearing procedures are dependent upon the instruments traded and any netting agreements or special commodity delivery procedures required for those instruments.  
         [0090]     The type 2 atomic unit is illustrated in  FIG. 4 . Type 2 enables client  4  to client  4  dealing among the clients  4  of a particular credit-bridging agent  5 , as well as enabling client  4  to credit-extending agent  5  trading. As usual, the anonymous order-matching process is triggered whenever an order to buy is made at a price equal to or higher than the lowest outstanding offer to sell, or vice versa. If the match is between a client  4  and the credit-bridging agent  5 , then a single deal is booked between those two parties  2 . However, if the match is between two clients  4 , then two back-to-back deals are booked, one between the seller client  4  and the credit-bridging agent  5 , and the other between the buyer client  4  and the credit-bridging agent  5 . This is akin to creating virtual trading channels between the clients  4 . A client  4  who has a credit relationship with the credit-bridging agent  5  is able to post its one-way or two-way order via computer  1 , which causes the order to be instantly displayed to all other clients  4  and to the credit-bridging agent  5  itself if the existing credit limits between the posting client  4 , the credit-bridging agent  5 , and the receiving client  4  would allow a portion of the order to be executed.  
         [0091]     This “mini-exchange” has the liquidity of the natural supply and demand of the entire client  5  base, combined with the market-making liquidity that the credit-bridging agent  5  would be supplying to its clients  4  ordinarily. It is certainly expected, and beneficial to the overall liquidity, that the credit-bridging agent  5  will be able to realize arbitrage profits between the prices posted by its clients  4  and the prices available to the credit-bridging agent  5  through other sources of liquidity. In fact, there may be instances in some markets where clients  4  are also able to arbitrage against other trading systems.  
         [0092]     Again, computer  1  provides several post-trade capabilities to the client  4  and to the trading desk, the back office, and the credit desk of the credit-bridging agent  5 , all in real-time, as in type 1.  
         [0093]     A pair of back-to-back trades is illustrated in  FIG. 5 , showing that agents  4 ( 2 ) and  4 ( 4 ) are the ultimate buyer and seller of the deal, but they each deal only with the credit-bridging agent  5  as their immediate counterparty  2 .  
         [0094]     As with all the various atomic units, central computer  1  updates the current tradable information after each trade, and causes this information to be displayed on the computers associated with all of the subscriber agents  2 .  
         [0095]     Again, computer  1  provides several post-trade capabilities to the clients  4 , as well as to the credit-bridging agent&#39;s  5  trading desk, its  5  back office, and its  5  credit desk, all in real-time. The credit-bridging agent  5  acts as a clearing agent for this trade, and is able to monitor the client-to-client exposure, in real time.  
         [0096]     Thus is created a price-discovery mechanism for end-users  2  with direct transparency between entities  2  wishing to take opposite sides in the market for a particular instrument. The present invention encompasses decentralized operation of an arbitrary number of separate, type-1 and type-2 atomic units. Efficient price discovery is provided to the end user  2  in a decentralized liquidity rich auction environment, leveraging existing relationships, and co-existing with and indeed benefiting from traditional trading methodologies.  
         [0097]     Furthermore, an arbitrary number of different type 0, type 1, and type 2 atomic units may be interconnected, bottom-up, as illustrated in  FIG. 6 , to provide, at all times, a liquidity rich efficient price-discovery mechanism to the subscribing agents  2 , enabling more and more agents  2 , across different atomic types, to conduct efficient direct auctions with each other directly. The various atomic units may be interconnected into a molecular credit-network.  
         [0098]     In  FIG. 6 , which may be considered to illustrate a “type 3” scenario, shaded circles represent credit-bridging agents  5  and un-shaded circles represent clients  4 .  
         [0099]     For purposes of simplicity, central computer  1  is not shown on  FIG. 6 , but is in fact coupled to all nodes  2 . Each node  2  has proprietary client software on a computer associated with said node  2 , enabling said node  2  to communicate with central computer  1 . Such software may take the form of a Web browser. The diameters of the arrow-headed lines  3  represent instrument excursion limits deduced from each trading channel&#39;s various types of credit limits. A “shortest weighted paths” algorithm or other minimum cost flow algorithm is used to calculate the minimal path between two agents  2  subject to credit flows to enable a trade between the agents  2 . The trading agents  2  may be arbitrarily removed from one another, both in geographic terms as well as by type of business activity in which they  2  are involved.  
         [0100]     Each connected piece of  FIG. 6  maintains full transparency of orders posted on computer  1  to all financial institutions  5  and clients  4  who are on any unexhausted credit path  3  to the posting entity  2 . Each of the entities  2  who are able to see the posted order are in effect competing, through the reverse auction, for that particular deal, enabling further efficient price-discovery to the posting entity  2 .  
         [0101]     Prior to each trade, computer  1  internally computes the values that define one of these  FIG. 6  graphs for each pair of instruments being traded. From the graph, computer  1  creates a table of multi-hop trading limits showing the trading limits between each pair of nodes  2 . From the table of multi-hop trading limits, computer  1  prepares a custom limit order book  24 , 25  for each node  2  for each traded instrument pair. After every trade, computer  1  recalculates the trading limits  3 , thus leading to a new graph ( FIG. 6 ) for that instrument pair. Recalculating the trading limits  3  for a given traded instrument pair can affect the topology (trading limits  3 ) of other graphs ( FIG. 6 ) for other traded instrument pairs. This can occur, for example, when the trading limits are notional trading limits.  
         [0102]     On  FIG. 6 , if an agent  2  has imposed its own internal limits that are smaller than the trading limits that have been imposed by a credit-extending agent  5  that is extending it  2  credit, computer  1  uses the smaller of the two limits when it creates  FIG. 6 .  
         [0103]     Each trading channel  3  represents an account between a credit-extending agent and a client agent  4 . In the preferred implementation of this invention, all credit-extending agents are credit-bridging agents  5 . Even when two adjacent nodes  2  are fully qualified to be credit-extending agents  5 , one acts as the credit-extending agent  5  in the transaction and the other acts as the client agent  4  in the transaction. The accounts that exist between credit-extending agents  5  and client agents  4  comprise specified input credit limits, balance holdings, and collateral; computer  1  calculates trading limits from this information.  
         [0104]     The operator of computer  1  typically has, in its standard agreement with a subscribing agent  2 , language stating that if the agent  2  has entered into a written subscription agreement with the operator of computer  1  and said agent  2  trades outside of the network  6 , 7  operated by the operator of computer  1 , that agent  2  is obligated to notify the operator of computer  1  about such outside trades, so that computer  1  can recalculate the trading limits as necessary.  
         [0105]      FIG. 6  can be thought of as an n-hop credit network, where n is an arbitrary positive integer. In any transaction, the instrument flow can fan out from one source node  2  and then collapse to the destination node  2 ; the instrument flow does not have to stay together as it flows from the source  2  to the destination  2 . See  FIG. 11  for an example of this phenomenon. In calculating the maximum capacity of the network  6 , 7 , computer  1  uses a maximum flow algorithm such as one described in chapter 7 of the Ahuja reference cited previously. In determining the actual flow used to complete the trade, computer  1  uses a minimum cost flow algorithm such as one described in chapter 9 of said Ahuja reference, where the cost to be minimized is a function of the actual cost to execute the trade and other factors, such as projected settlement costs, flow balancing heuristics, and a randomizing component.  
         [0106]     The network  6 , 7  of  FIG. 6  is a non-disjointed network. By that is meant that every node  2  in the network  6 , 7  is coupled to at least one other node  2 , and at least one of the agents  2  associated with each trading channel  3  is a credit-bridging agent  5 . The individual trading limits  3  that computer  1  computes for each agent  2  pair are dependent upon the topology of the network  6 , 7 . Computer  1  essentially transforms the network  6 , 7  into a virtually cliqued networked. A “cliqued network” is one in which every node  2  is connected to every other node  2 . A “virtually cliqued network” is one in which every node  2  has a capability to trade with every other node  2 , but not necessarily directly. In order to preserve the desired feature of anonymity, each node  2  knows the identities of only its immediate trading partners  2 , and does not necessarily know whom  2  it is actually trading with.  
         [0107]     As a trading system that leverages the existing relationships in the market for the traded instrument, the present invention provides all market players  2  (typically banks, financial institutions, clearing entities, hedge funds, and any corporations or other entities) the ability to trade directly with each other through a custom limit order book  24 , 25 . These agents  2  may already be connected together with credit relationships, but prior art systems allow trading only between two parties that have an explicit credit arrangement. The present invention analyzes the credit-worthiness of a potentional counterparty  2  at a higher level, performing this analysis in real time, and providing each party  2  with a limit order book  24 , 25  customized to its  2  current credit availability.  
         [0108]     For example, in  FIG. 7  we consider a small network of foreign exchange players: banks  5 (B) and  5 (C), which have a credit relationship with each other, and clients  4 (A) and  4 (D), who have margin placed with banks  5 (B) and  5 (C), respectively (we leave the margin currency and traded instrument unspecified). The specified input credit limits are specified as traded instrument L:Q credit limits (just one way of specifying input credit limits out of eight possible ways enumerated in the present patent application). Client  4 (A)&#39;s margin allows it to trade +/− 10M with  5 (B),  5 (B)&#39;s relationship allows it to trade +/− 50M with  5 (C), and 5(D)&#39;s margin allows it to trade +/− 5M with  5 (C). This information is supplied to computer  1 , which draws  FIG. 7  from said information.  
         [0109]      FIG. 7  illustrates a simplified type 3 network in which there are two client agents  4  and two credit-extending agents  5  which are also credit-bridging agents  5 .  FIG. 7  also illustrates the trading limits between each pair of coupled agents  4 , 5 . Table 1 shows the maximum multi-hop credit limits that are then calculated by computer  1  for the simplified network of  FIG. 7  as follows:  
                                                         TABLE 1                                   A   B   C   D                                    A   infinity   10 M   10 M   5 M       B   10 M   infinity   50 M    5 M       C   10 M   50 M   infinity   5 M       D    5 M    5 M    5 M   infinity                    
         [0110]     Computer  1  then uses the information contained in Table 1 to create a custom limit order book  24 , 25  for each agent A, B, C, D, and causes the custom limit order book  24 , 25  to be displayed on the computer screen of the respective agent A, B, C, D. The filtered bids and offers in the custom limit order book  24 , 25  are for volumes that are an integral multiple of the lot size even if the computed Table 1 amounts contain values which are not integral multiples of the lot size, with non-integral multiples rounded toward 0.  
         [0111]     If client A posts a bid for 10M, computer  1  causes the full bid to appear on the custom limit order books  24 , 25  of banks B and C, and computer  1  causes a filtered bid for 5M to appear on the custom limit order book  24 , 25  of client D, because the maximum credit (implicit or explicit) available between A and D is +/−$5M. If there is no implicit or explicit credit available between two nodes  2 , they  2  are not allowed to see each other&#39;s bids and offers at all on their custom limit order books  24 , 25 .  
         [0112]     The network  6 , 7  of the present invention is preferably built using the Internet Protocol (IP) (because of its ubiquity), and may reside on the Internet itself or other public IP network  7  ( FIG. 8 ).  
         [0113]     It is also possible to locate part or all of the network  6 , 7  on a private fiber backbone  6 , so that information bound for the Internet  7  can traverse most of the distance to its destination on the presumably higher speed private network  6 . The slower public Internet  7  is then used for just the last segment of travel. It is also possible to provide clients  2  with dedicated bandwidth through private IP networks  6  in order to provide additional levels of quality and service. A single dedicated connection  6  may be backed up by an Internet connection  7 , or multiple private connections  6  can be used to avoid the public network  7  entirely.  
         [0114]     On  FIG. 8 , the three illustrated agents  2  can be three separate companies, three computers within the same company, or a hybrid of the above.  
         [0115]     The network  6 , 7  interfaces with both people and automated systems (computers), so it provides three access methods: 
        human—Graphical User Interface (standalone or browser-based application) for trading, interactive queries, and account management;     human/computer—HTTP reports interface (HTML, XML, PDF, or Excel) for queries only;     computer—Application Programming Interface  38  (available in Java and COBRA with bridges to FIX, JMS, SOAP, and ebXML) for trading, queries, and account management.        
 
         [0119]     An agent&#39;s  2  software can be launched from the agent&#39;s  2  browser but run as a standalone application for better performance and stability.  
         [0120]     The computer of each agent  2  can have associated therewith an application programming interface (API)  38 . The API  38  is a standard interface exposed by the central computer  1  that enables the user  2  to write customized instructions enabling two-way communication between central computer  1  and the user  2 . In the case where the user  2  is a credit extending agent  5 , the API  38  can be used to update the agent&#39;s backoffice information. The agent  2  can program his API  38  to make and cancel orders (bids and/or offers). The agent  2  can use his API  38  to receive and reformat custom limit order books  24 , 25  for any instruments. The agent  2  can use his API  38  to set trading limits, with the understanding that the actual trading limits are the minimum of the trading limits specified by the two agents  4 , 5  associated with an account. The API  38  can be programmed to estimate how much it would cost an agent  2  to liquidate his position in an instrument. The API  38  can be programmed to estimate that agent&#39;s profit/loss amount for each instrument being traded; this information can be combined with the agent&#39;s custom limit order book  24 ,  25 . Anything that can be achieved by the GUI (graphical user interface) ( FIGS. 13-22 ) can be achieved via the API  38 .  
         [0121]     Any and all features of the API  38  can be programmed to operate automatically, including automatic bidding, offering, buying, and selling. Automated processes accessing computer  1  via application programming interface  38  or a bridge use the same cryptographic protocols as for a human agent  2  inputting instructions via his computer&#39;s GUI. Whether an API  38  or a GUI is used, an agent&#39;s private key for computerized access to computer  1  can be stored in the agent&#39;s computer, provided said computer has sufficient security safeguards.  
         [0122]     Privacy, authentication, and non-repudiation are achieved in the present invention via the use of cryptography in a variety of different forms. The cryptographic techniques can comprise symmetric key and/or asymmetric key (public key) cryptography. All data streams are encrypted, e.g., by using SSL (Secure Socket Layer) connections or a combination of SSL encryption with additional authentication and encryption. Authentication can be required between computer  1  and an agent  2  at any and all times these devices  1 , 2  communicate with each other. This authentication can be achieved through the use of digital certificates. Revalidation of credentials can be required at the time a trade is consummated.  
         [0123]     Each agent  2  may store its private key on a tamper-resistant hardware device such as a smartcard, protected by a password. The combination of a physical token (the card) with a logical token (the password) ensures two levels of security. The hardware token may contain a small CPU that allows it to perform the necessary cryptographic operations internally, so that the agent&#39;s private key never leaves the smartcard. In a preferred embodiment, computer  1  handles bulk encryption/decryption using symmetric key cryptography after the slower public key cryptography has been used to exchange a session key between agent  2  and computer  1 .  
         [0124]     While trading in the present invention is peer-to-peer, order matching for any particular instrument is done at a centralized location  1  to maintain transactional integrity.  FIG. 9  illustrates the order matching process. In step  8 , the first agent  2 ( 1 ) places a bid via its software to computer  1 , which accepts the bid at step  9 . Computer  1  then calculates changes to the custom limit order books  24 , 25  of agents  2 ( 1 ) and  2 ( 2 ) at steps  10  and  11 , respectively, taking into account appropriate trading limits  3 . At step  12 , the second agent  2 ( 2 ) takes the bid. Step  12  occurs right before step  13 , in which a third agent  2 ( 3 ) (not illustrated) posts a new offer (bid or offer) for the traded instrument L: Q. At step  14 , computer  1  makes the match between the first agent  2 ( 1 ) and the second agent  2 ( 2 ).  
         [0125]     Reporting of the trade is described below in conjunction with  FIGS. 35 and 36 .  
         [0126]     A network  6 , 7  implementing the present invention can span the entire world, which means that there may be time differences for a message sent by different agents  2  to computer  1 . Assuming a network  6 , 7  that sends signals at the speed of light but that cannot transmit through the Earth, a message sent to the other side of the Earth would have a round-trip time of at least 130 milliseconds. On existing IP networks, it is observed that if the central computer  1  were located in New York, the maximum average round-trip communication time between the central computer  1  and a computer in any of the major financial centers is less than 300 milliseconds.  
         [0127]     We want to ensure that all agents  2  have a level playing field in accessing computer  1 , regardless of where these agents  2  are situated around the world. Determining the latency for each agent  2  and then introducing an individual delay on an agent-by-agent basis to try to equalize time-of-arrival at computer  1  would be very difficult (due to short term fluctuations in network  6 , 7  lag), and could have the undesired effect of overcompensating. A malicious agent  2  could also falsify its network  6 , 7  delay, unfairly obtaining early access to computer  1 .  
         [0128]     In order to compensate for the various time lags in sending messages between agents  2  and computer  1  on a global basis, the present invention transmits information as rapidly as possible while flagging the order of messages to compensate for latency. The flagging is done by means of border outpost computers  16  ( FIG. 10 ).  
         [0129]     For agents  2  remote from computer  1 , a border outpost computer  16  is inserted into the network  6 , 7 , typically where the agent&#39;s data enters the private backbone  6  that connects to computer  1 . Each border outpost computer  16  comprises a CPU  18 , a trusted time source  17 , and an input/output port  19 . Time source  17 , which may comprise a GPS clock accurate to a millionth of a second, is used to generate a digital time stamp that is added to each data packet before it is forwarded to computer  1 . The GPS clocks  17  of all the border outpost computers  16  are synchronized with each other to a high degree of accuracy (typically one microsecond). The time stamp may be placed onto the packet without the border outpost computer  16  having to understand the packet or have access to its contents. At the computer  1  site, the time stamp is stripped off before the packet is processed, and then reassociated with the data after it is decrypted and parsed into a command. Computer  1  then sorts the messages into a queue by time order. After a fixed time delay, the message that is at the front of the queue is serviced by computer  1 . The fixed time delay is chosen so that with a high degree of certainty a message from the remotest agent&#39;s  2  computer will arrive at computer  1  within the fixed time delay. The purpose of the fixed time delay is to allow all messages that might be the first-originated message to have a chance to arrive at computer  1  before execution of any messages takes place. The time stamp may be encrypted using either a symmetric or assymetric cipher, to prevent its modification or falsification.  
         [0130]      FIG. 11  is a deal fulfillment (flow) graph, illustrating the flow in the lot instrument. The lot instrument L is the portion of the traded instrument that has to be traded in a round lot, typically a multiple of a million. The quoted instrument Q is that portion of the instrument being traded that is expressed as the lot instrument times a price. In this example, agent  4 ( 2 ) buys 10M Euros using U.S. dollars at an exchange rate of 0.9250 from agent  4 ( 1 ). Since the Euro is the lot currency in this example, it has to be specified in a round lot (multiple of 1 million Euros). F(L), the lot size (volume), is 10 million and F(Q), the quoted volume, is 9,250,000. In this example, there are three intermediaries (middlemen): agents  5 ( 1 ),  5 ( 2 ), and  5 ( 3 ). Only credit-bridging agents  5  can be middlemen. For purposes of simplification, we show on  FIG. 11  the flow of just the lot instrument L. There is also a counterflow in the quoted instrument Q, which can be derived from the lot flow and the traded price. For example, on the edge  3  between node  5 ( 1 ) and  4 ( 2 ,) 2M represents the flow of 2 million Euros from agent  5 ( 1 ) to agent  4 ( 2 ), as well as the counterflow of 1,850,000 U.S. dollars from agent  4 ( 2 ) to agent  5 ( 1 ).  
         [0131]      FIG. 12 , a simplified focus change diagram, illustrates the sequence of screen shots appearing on the display of a computer of an agent  2  who is coupled to central computer  1 . Agent  2  first encounters a log-in dialog box  21 , then a menu bar  22  where he can select from an account management dialog box  23 , a net exposure screen  35 , a balance sheet  36 , or his custom limit order book  24 , 25 . From custom limit order book overview screen  24 , agent  2  can navigate to one of N order book detail screens  25 , or to an activity dialog screen  27 , which can take the form of a bid dialog box  28 , an offer dialog box  29 , a buy dialog box  30 , a sell dialog box  31 , or a market order screen  32 . As shown in  FIG. 12 , various of these screens can segue into a bid/offer cancel dialog box  33  or a confirmation dialog box  34 .  
         [0132]      FIGS. 13-22  illustrate most of the above screens. The login screen is shown ( FIG. 13 ), followed by two shots of the main desktop ( FIGS. 14 and 15 ) showing the custom limit order book overview window  24  and the custom limit order book detail window  25 . The remaining screen shots ( FIGS. 16-22 ) are of dialog boxes that can be activated from either the overview window  24  or detail order windows  25 .  
         [0133]      FIG. 13  illustrates log-in dialog box  21 . Field  41  allows agent  2  to type in his name, thus identifying the account and trader. Field  42  is an optional challenge field, provided for security purposes. An appropriate response from the agent  2  to meet the challenge might include presentation of a password, key, or digital certificate via a hardware token. Field  43  is where agent  2  enters his password. Field  44  is where agent  2  enters the address of central computer  1 . In the case of an Internet connection, the URL of computer  1  is specified here. The data exchange between agent  2  and central computer  1  is encrypted, e.g., by a SSL (Secure Socket Layer) connection. Field  45  is a scrolling message log showing status and notification of errors during the log-in process.  
         [0134]      FIG. 14  illustrates the main custom limit order book screen. Field  51  specifies the current account. Field  52  is a summary of the custom limit order book for each permissioned traded instrument. In this sample, where the instruments are pairs of currencies, the traded instruments are identified by icons representing the flags of the countries issuing the currencies. There are five fields  52  illustrated, representing five permissioned instruments. The second field  52  from the top (Great Britain pounds for U.S. dollars) is exploded, indicating the traded instrument currently activated by agent  2 .  
         [0135]     Field  53  displays the top (best) orders from the point of view of the agent  2 . Field  54  displays the best bid price for any agent  2  coupled to the network  6 , 7 . Field  55  displays the last two digits (“84”) of the best available bid price. Field  56  displays the size at the best bid price. Field  57  displays agent  2 &#39;s available liquidity for additional selling. Field  58  provides agent  2  with a mouse-clickable area (the big figure) enabling the agent  2  to jump to the buy or sell dialog screen  30  or  31 , with amounts already filled in. Field  59  is a mouse-clickable numeric keypad allowing the agent  2  to create and cancel orders. Field  60  gives balance sheet values showing live valuations at market price and the profit that was banked by agent  2  for a certain period of time, such as the current day. Field  61  is a pop-up console allowing for the display of application messages, connection failure/retry messages, and broadcast messages from central computer  1 . Field  62  displays the time since the agent  2  has logged in to computer  1 . Field  63  displays the best available offer; in this case, four digits of the available offer are used to warn agent  2  that his best available offer is far from the overall best, due to a credit bottleneck. Field  64  shows this agent&#39;s orders in red. Field  65  shows, this agent&#39;s current net position in the instrument being traded. Field  66  shows a summary of this agent&#39;s offers. Field  67  is a mouse-clickable area (tab  9 ) enabling the agent  2  to quickly cancel the top offer.  
         [0136]      FIG. 15  illustrates a custom limit order book depth window  25 . There are N of these windows  25  for each instrument, where N is any preselected positive integer. Typically, N is equal to five. The N windows  25  display the N best bids and offers in order of price, and within price, in order of date and time, with the oldest presented first. Field  71  shows bid and offer information, with the last two digits of the bid and offer (“99” and “02”, respectively) displayed in large numerals for readability. Field  72  shows visible (to that agent  2 ) bids and offers truncated by current credit availability, individually or aggregated by price (configurable). Bids and offers from this agent&#39;s account are shown in pink. Field  73  is a mouse-clickable field allowing agent  2  to navigate to screen  33  ( FIG. 18 ). Field  74  is a set of four mouse-clickable areas enabling agent  2  to open buy, sell, bid, and offer dialog boxes ( 30 ,  31 ,  28 , and  29 , respectively), with price and size information pre-loaded from the current market.  
         [0137]      FIG. 16  illustrates net exposure monitor  35 . Each entry  81  gives the current exposure for each account, broken down by traded instrument. Field  82  (“min” and “max”) shows asymmetric net position limits on a per-instrument basis. Field  83  (“current”) shows a real-time update of net position. Field  84  shows a graphical representation of net position.  
         [0138]      FIG. 17  illustrates balance sheet window  36 . Field  91  shows payables and receivables, valued using the current market price. Total net position and net position for each counterparty  2  are given. Field  91  is organized as a tree hierarchy, and allows navigation to individual balance sheet transfers. Field  94  shows underlying flows; they have been sent to the agent&#39;s computer in an encrypted form, and are decrypted at the agent&#39;s computer. The decryption can be done automatically, as long as the agent  2  is logged in to the network  6 , 7 . In field  94 , one line represents each trade this agent  2  has made, or each trade for which this agent  2  was an intermediary  5 . All values are live. This currency-based balance sheet  36  is capable of handling triangular instrument swaps.  
         [0139]      FIG. 18  illustrates the open order overview and management window  33 . Field  101  shows orders (bids and offers) currently placed by that agent summarized by traded instrument. Field  102  shows individual orders. Field  103  is a mouse-clickable area enabling the agent  2  to remove the order from the agent&#39;s custom limit order book  24 , 25 . All values are updated immediately if their value has changed. In screen  33 , an update procedure can be implemented in which the first offer is not cancelled until a new offer is posted. This is sometimes referred to as OCO (one cancels the other). In any event, it is never possible for an agent  2  to cancel an order after it has been taken by a counterparty  2 .  
         [0140]      FIG. 19  illustrates bid creation dialog box  28 . Field  111  is a group of icons, typically in various colors to provide visual context to reduce errors. Note that the word “Bid” is highlighted. Field  112  comprises three mouse-clickable areas allowing for quick up or down adjustment of price and direct entry of price, respectively, with initial value taken from the current market. Field  113  comprises three mouse-clickable areas allowing for quick up or down adjustment of size, and direct entry of size, with initial value configurable based upon the desires of the particular agent  2 . Field  114  is a mouse-clickable area allowing the agent  2  to submit the bid, and has an optional confirmation dialog box associated therewith. An agent  2  can post his bid for just a short period of time and then withdraw it. He  2  can post multiple bids at multiple prices. When a counterparty  2  takes part or all of his bid, computer  1  recalculates the trading limits. Agent  2  can make his bid limited to “only if it is available now” or as an offer to buy.  
         [0141]      FIG. 20  illustrates offer creation dialog box  29 . Field  121  comprises a set of icons, typically colored to provide visual context to reduce errors. Note that the word “Offer” is highlighted. Field  122  comprises three mouse-clickable areas allowing agent  2  to quickly achieve up or down adjustment of price and direct entry of price, with initial value taken from the current market. Field  123  comprises three mouse-clickable areas providing a quick means for agent  2  to achieve up or down adjustment of size and direct entry of size, with initial value configurable on a per user  2  basis. Field  124  is a mouse-clickable area allowing agent  2  to post the offer, and has an optional confirmation dialog box associated therewith.  
         [0142]      FIG. 21  illustrates buy (immediate execution bid) dialog box  30 . Field  131  comprises a set of icons, typically colored to provide visual context to reduce errors. Note that the word “Buy” is highlighted. Field  132  comprises three mouse-clickable areas, providing a quick means for up or down adjustment of price and direct entry of price, with initial value taken from the current market. Field  133  is a mouse-clickable button allowing for a partial execution of a trade. This allows agent  2  to buy either as much of the size as possible, or nothing if he cannot buy the entire size. Field  134  comprises three mouse-clickable areas providing a quick means for up or down adjustment of size and direct entry of size, with initial value configurable on a per user  2  basis. Field  135  is a mouse-clickable area allowing agent  2  to execute the buy, and has an optional confirmation dialog box associated therewith.  
         [0143]      FIG. 22  illustrates sell (immediate execution offer) dialog box  31 . Field  141  is a set of icons, typically colored to provide visual context to reduce errors. Note that the word “Sell” is highlighted. Field  142  comprises three mouse-clickable areas providing a quick means for agent  2  to achieve up or down adjustment of price and direct entry of price, with initial value taken from the current market. Field  143  is a mouse-clickable area allowing partial execution. This allows agent  2  the choice of the sell being either to fill as much of the size as possible, or to not sell if he  2  cannot sell the entire size. Field  144  comprises three mouse-clickable areas providing for a quick means for up or down adjustment of size and direct entry of size, with initial value configurable on a per user  2  basis. Field  145  is a mouse-clickable area allowing the sell to be executed, and has an optional confirmation dialog box associated therewith.  
         [0144]      FIG. 23  is a flow diagram illustrating the method steps by which computer  1  computes a custom limit order book  24 , 25  for a single agent  2  for a single traded instrument. Even intermediate agents  5  get a custom limit order book  24 ,  25 . For the left hand side of  FIG. 23 , source S is that node  2  for which this custom limit order book is being prepared; and sink T is that node  2  that has posted the bid. For the right hand side of  FIG. 23 , source S is that node  2  that posted the offer; and sink T is that node  2  for which this custom limit order book is being prepared. “Source” and “sink” are standard network terminologies; see, e.g., the Ahuja reference previously cited. These concepts are used internally by computer  1 , but are not disclosed to all agents  2  for reasons of preserving the desired anonymity. For example, the actual poster  2  of the offer does not appear on the screen of the counterparty  2 .  
         [0145]     The method starts at step  151 . In step  152 , computer  1  asks whether there have been any trades made since the last multi-hop credit computation. This is meant to avoid unnecessary computation. If the answer to the question is “yes”, then step  153  is executed. At step  153 , multi-hop credit limits are computed, as illustrated in  FIG. 24 . If the answer to the question raised in step  152  is “no”, step  154  is executed. At step  154 , the bid side of the book is cleared, i.e., variable B becomes the null set; the offer side of the book is cleared, i.e., variable A becomes the null set; and the credit used (U as a function of S and T) is cleared. In this context, “used” applies only for this particular custom limit order book  24 , 25  for this particular agent  2 . Step  155  is then executed, where it is asked whether enough bids have been found. “Enough” is a pre-established limit, e.g., five, and corresponds to N as discussed above in conjunction with custom limit order book detail window  25 . N may be infinity, in which case the method always proceeds from step  155  to step  156 . If enough bids have been found, the method proceeds to step  161 . If enough bids have not been found, the method proceeds to step  156 , where it is asked whether there are more unprocessed bids, i.e., if the number of bids that have been processed is less that the pre-established limit. If the answer is “no”, step  161  is executed; otherwise, the method proceeds to step  157 , where the highest priced oldest unprocessed bid is fetched. The hierarchy is according to highest bid. If there is a tie as to two or more highest bids, then the bids are ordered by time. It is forced that there not be a time-tie at this point; time collisions have already been resolved by locking using sequence numbers.  
         [0146]     Step  158  is then executed. X is defined as the flow limit (trading limit) between S and T minus the credit U between S and T that has already been used up. Y is then set to be the minimum of X and the bid size. In other words, Y is what we have to work with. Step  159  is executed, where it is asked whether Y is greater than 0. If not, the method cycles back to step  155 . If “yes”, step  160  is executed. In step  160 , the set of bids B is augmented by the current bid we are working with from step  157 . Also in step  160 , the credit used U is augmented by Y.  
         [0147]     At step  161 , it is asked whether enough offers have been found. Again, “enough” is a pre-established limit e.g., five, corresponding to N as before. If the answer to this is “yes”, the method stops at step  167 . If the answer is “no”, step  162  is executed. At step  162 , it is asked whether there are more unprocessed offers. If not, the method ends at step  167 . If “yes”, step  163  is executed, where the lowest priced, oldest unprocessed offer is fetched. Then, step  164  is executed, where X is set to be the trading limit between S and T minus the unused credit U. Y is then set to be the minimum of X and the offer size. Step  165  is then executed. At step  165 , it is asked whether Y is greater than 0. If not, control is passed back to step  161 . If “yes”, step  166  is executed, where the current offer price being worked on from box  163  is added to the set of offers A; and the credit used U is augmented by Y. Control then passes back to step  161 .  
         [0148]      FIG. 24  illustrates how computer  1  calculates multi-hop trading limits for each pair of agents  2  for a single traded instrument L:Q, i.e., how computer  1  performs step  153  on  FIG. 23 . This is akin to compiling a table like Table 1 shown above. This procedure starts at step  171 . At step  172 , a directed graph is computed for the traded instrument L:Q, in which the arrow corresponds to the direction of flow of the lot instrument L. Individual trading limits are introduced at this point. Step  172  is the subject of  FIG. 25 . At step  173 , an arbitrary network node  2  is selected to be the first node worked upon by the process and is given the designation source S. At step  174 , sink T is also set to be said first network node  2 . At step  175 , it is asked whether S is equal to T. If so (which, of course, is the case initially), the procedure moves to step  176 , where the maximum flow limit between S and T is set to be infinity. This is simply another way of saying that an agent  2  is allowed to have an infinite flow with himself  2 . Then, at step  182 , it is asked whether T is the last network node that needs to be processed. If “yes”, control is passed to step  184 ; if “no”, control is passed to step  183 , where T is advanced to the next network node; and control is passed back to step  175 . “Next” can be anything, because the order of processing is of no import.  
         [0149]     If S is found not to be equal to T at step  175 , control is passed to step  177 , which disables edges  3  where the edge origin  2  is not a credit bridge  5  and the edge origin  2  is not equal to S. An edge  3  may be disabled internally by adjusting its maximum capacity to 0 or by removing it from the set of edges  3  that comprise the graph. The “edge origin” is that node  2  from which the lot instrument L flows. Steps  177  and  178  eliminate agents  2  who have not agreed in advance to be intermediaries, i.e., “credit bridges”. An intermediary (credit bridge) is an agent  5  that allows two other agents  2  to do back-to-back trades through the intermediary agent  5 . Step  178  disables edges  3  where the edge destination  2  is not a credit bridge  5  and the edge destination  2  is not equal to T. An “edge destination” is a node  2  that receives the flow of the lot instrument L.  
         [0150]     At step  179 , the maximal flow from S to T is computed using a maximal flow algorithm such as one of the algorithms disclosed in Chapter 7 of the Ahuja reference previously cited. At step  180 , the multi-hop credit limit between S and T, LIM(S,T), is set to be equal to the maximum flow obtained from step  179 . At step  181 , the edges  3  that were disabled in steps  177  and  178  are re-enabled. Step  184  asks whether S is the last network node to be processed. If “yes”, the procedure concludes at step  186 . If “no”, the process moves to step  185 , where S is advanced to the next network node. Again, “next” is arbitrary and simply refers to any other unprocessed node  2 . After step  185 , the method re-executes steps  174 .  
         [0151]      FIG. 25  illustrates how computer  1  calculates a directed graph for the traded instrument L:Q, i.e., how computer  1  performs step  172  of  FIG. 24 . This is akin to producing a graph such as that shown in  FIG. 6 , with arrows as in  FIG. 11 . The operation commences at step  191 . At step  192 , the edge  3  set G is nulled out. At step  193 , computer  1  searches its records for any account A that it has not yet processed. The order of selection of unprocessed accounts is irrelevant. Account A is any pre-existing trading (credit) relationship between two neighboring agents  2  that has been previously conveyed to the operator of computer  1  in writing in conjunction with these agents  2  subscribing to the trading system operated by the operator of computer  1 .  
         [0152]     Step  194  asks whether there is any such unprocessed account A. If “not”, this process stops at step  198 . If there is an unprocessed account A, the process executes step  195 , where the minimum and maximum excursions for account A are calculated. Step  195  is the subject of  FIG. 26 . These minimum and maximum excursions are defined in terms of the lot instrument L, and are calculated from one or more of eight possible ways of specifying input credit limits. The maximum and minimum excursions are excursions from current position. The input credit limits are specified as part of each account A. In step  196 , the set of edges G is augmented with an edge  3  from A&#39;s lender  2  to A&#39;s borrower  2 , with the capacity of the edge  3  being set to the maximum excursion. L is the lot instrument and Q is the quoted instrument. In step  197 , the set of edges G is augmented with an edge  3  from A&#39;s borrower  2  to A&#39;s lender  2 , with the capacity of the edge  3  being set to the negative of the minimum excursion. The process then re-executes step  193 .  
         [0153]      FIG. 26  shows how computer  1  calculates the minimum and maximum excursions for a single account A and a single traded instrument L:Q, i.e., how computer  1  executes step  195  of  FIG. 26 . This computation takes into account up to eight different ways a guaranteeing agent  5  may specify input credit limits in an account A. The operation commences at step  201 . At step  202 , the maximum excursion is set to be infinity and the minimum excursion is set to be minus infinity, because at this point there are no trading limits.  
         [0154]     Step  203  asks whether position limits have been defined for the lot instrument. If yes, step  204  is executed. At step  204 , the lot instrument position limits&#39; effects on the maximum and minimum excursions are calculated. This is the subject of  FIG. 27 . At step  205 , it is asked whether volume limits have been specified for the lot instrument. If so, step  206  is executed. At step  206 , the lot limit volume limits&#39; effects on the maximum and minimum excursions are calculated. This is the subject of  FIG. 29 . At step  207 , it is asked whether position limits have been specified for the quoted instrument. If so, step  208  is executed. At step  208 , the quoted instrument position limits&#39; effects on the maximum and minimum excursions are calculated. This is the subject of  FIG. 28 . At step  209 , it is asked whether volume limits have been specified for the quoted instrument. If so, step  210  is executed. At step  210 , the quoted instrument volume limits&#39; effects on the maximum and minimum excursions are calculated. This is the subject of  FIG. 30 . At step  211 , it is asked whether notional position limits have been specified. If so, step  212  is executed. At step  212 , the notional position limits&#39; effects on the maximum and minimum excursions are calculated. This is the subject of  FIG. 31 . At step  213 , it is asked whether notional volume limits have been specified. If so, step  214  is executed. At step  214 , the notional volume limits&#39; effects on the maximum and minimum excursions are calculated. This is the subject of  FIG. 32 . At step  215 , it is asked whether position limits have been specified for the traded instrument L:Q. If so, step  216  is executed. At step  216 , the traded instrument L:Q position limits&#39; effects on the maximum and minimum excursions are calculated. This is the subject of  FIG. 33 . At step  217 , it is asked whether volume limits have been specified for the traded instrument L:Q. If so, step  218  is executed. At step  218 , the traded instrument L:Q volume limits&#39; effects on the maximum and minimum excursions are calculated. This is the subject of  FIG. 34 .  
         [0155]     Then step  219  is executed, where the maximum excursion is set to be equal to the maximum of 0 and the current value of the maximum excursion. This is done because we don&#39;t want to have a negative maximum excursion. At step  220 , the minimum excursion is set to be the minimum of 0 and the current value of the minimum excursion. This is done because we do not want to have a positive minimum excursion. Then, the method ends at step  221 .  
         [0156]     It is important to note that the order of taking into account the effects of the eight types of specified input credit limits is irrelevant, because each of the eight can only constrict an excursion more, not expand it. Therefore, the ultimate limit is the most restrictive one. All of the eight trading limits described herein are recalculated after each trade affecting that limit.  
         [0157]     As used herein, a “trading limit” is something calculated by computer  1 , and a “credit limit” is something specified by a guaranteeing agent  5 .  
         [0158]     Conventional mathematical shortcuts can be used to speed the calculations without necessarily having to repeat all the method steps in all but the first time a particular method is executed. All of the steps of  FIG. 26  get executed the first time a method shown in  FIGS. 27 through 34  is executed.  
         [0159]      FIG. 27  shows how computer  1  calculates the position limit for the lot instrument, i.e., how computer  1  performs step  204  of  FIG. 26 . A position limit is a net limit in the instrument being traded. The method starts at step  231 . At step  232 , computer  1  retrieves the specified input maximum position credit limit for instrument L, PMAX(L), and the specified input minimum position credit limit for instrument L, PMIN(L). Normally, PMIN(L) is the negative of PMAX(L), but that doesn&#39;t necessarily have to be true. Also in step  232 , the net position, POS, is zeroed out.  
         [0160]     In step  233 , computer  1  looks for another unsettled flow of instrument L in account A. “Another” is arbitrary. At step  234 , it is asked whether such another unsettled flow exists. If not, control passes to step  238 . If the answer is “yes”, step  235  is executed, wherein it is asked whether the flow is to account A&#39;s borrower  2 . A “flow” is a transfer of a single instrument along a single edge  3 . This is the same as asking whether the flow is to other than a guaranteeing agent  5 , because the lender is the guaranteeing agent  5 . If the answer is yes, step  236  is executed, during which POS is augmented by the flow amount, and control passes back to step  233 . This inner loop  233 - 236  constitutes calculation of the net position, and is performed for each Q matching that L.  
         [0161]     If the answer to the question posed in step  235  is “no”, step  237  is executed, wherein POS is decremented by the flow amount, and control is passed back to step  233 . At step  238 , X is set to be equal to PMAX(L) minus POS, and Y is set equal to PMIN(L) minus POS. X is the maximum excursion from this flowchart and Y is the minimum excursion from this flowchart. At step  239 , the maximum excursion for the traded instrument L:Q is set to be equal to the minimum of the current value of this maximum excursion and X; and the minimum excursion for the traded instrument L:Q is set to be equal to the maximum of the minimum of the current value of the minimum excursion and Y. In other words, the set of maximum and minimum excursions is updated based upon the results of this flowchart. The method ends at step  240 .  
         [0162]      FIG. 28  illustrates how computer  1  calculates the position limit for the quoted instrument, i.e., how computer  1  performs step  208  of  FIG. 26 . Other than the fact that Q is substituted for L, the method described in  FIG. 28  is identical to that described in  FIG. 27 , with one exception: in step  259  (analogous to step  239  of  FIG. 27 ), we convert from the quoted instrument to the lot instrument, because we want everything expressed in terms of the lot instrument once we get to the higher level flowchart ( FIG. 26 ). Therefore, in step  259 , X and Y are each multiplied by a “fixed rate Q:L” (exchange rate). This exchange rate is fixed for a certain period of time, e.g., one hour or one day, and may be different for different accounts at the same moment in time.  
         [0163]      FIG. 29  illustrates how computer  1  calculates the volume limit for the lot instrument, i.e., how computer  1  performs step  206  of  FIG. 26 . A volume limit is a gross limit in the instrument being traded. The method starts at step  271 . In step  272 , computer  1  retrieves the specified input maximum permissible volume credit limit for instrument L, VMAX(L); and clears a variable field VOL representing total volume. In step  273 , computer  1  looks for another unsettled flow of instrument L in account A. “Another” is arbitrary. At step  274 , it is asked whether such another unsettled flow has been found. If “yes”, at step  275 , VOL is augmented with the flow amount. It doesn&#39;t matter whether the flow is in or out to a particular node  2 ; it counts towards the volume limit the same in each case.  
         [0164]     Control is then passed back to step  273 . If the answer posed in step  274  is “no”, step  276  is executed, wherein X is set equal to VMAX(L) minus VOL, and Y is set equal to minus X, because of the definition of “volume”. Again, X and Y are the partial limits as calculated by this particular flowchart. Then in step  277 , the maximum excursion is set equal to the minimum of the previous value of the maximum excursion and X; in the minimum excursion is set equal to the maximum of the previous value of the minimum excursion and minus X. In other words, the overall excursions are updated based upon the results of this flowchart. The method then ends at step  278 .  
         [0165]      FIG. 30  illustrates how computer  1  calculates the volume limit for the quoted instrument, i.e., how computer  1  performs step  210  of  FIG. 26 . Other than the fact that Q is substituted for L, the method steps of  FIG. 30  are identical to those of  FIG. 29 , with one exception: in step  287  (analogous to step  277  of  FIG. 29 ), X and minus X are each multiplied by “fixed rate Q:L” for the same reason that this factor was introduced in  FIG. 28 .  
         [0166]      FIG. 31  illustrates how computer  1  calculates the notional position limit, i.e., how computer  1  performs step  212  of  FIG. 26 . The notional position limit protects the guaranteeing agent  5  against rate excursions aggregated over the positions in all of the instruments. “Notional” means we are changing the notation; the concept implies that there is a conversion from one instrument to another, and that the conversion is done at a certain rate that has been agreed upon. The rate is set periodically, e.g., daily. This conversion from one instrument to another is used to convert all values into a single currency for the purpose of aggregation into a single value.  
         [0167]     The method commences at step  291 . At step  292 , computer  1  retrieves the maximum notional position credit limit PMAXN, where N is the notional instrument, i.e, the instrument in which the limit is presented. In step  292 , the notional position, NPOS, is also zeroed out. In step  293 , computer  1  looks for another instrument C with flows in account A. C is an index designating the instrument for which we are executing the loop  293 - 301 . The order of selecting the instruments is immaterial. Step  294  asks whether such another instrument C has been found. If not, control passes to step  302 . If the answer is yes, step  295  is executed, wherein the instrument position, POS(C), is zeroed out. At step  296 , computer  1  looks for another unsettled flow of instrument C in account A.  
         [0168]     Step  297  asks whether such another unsettled flow has been found. If not, control passes to step  301 . If the answer is “yes”, step  298  is executed, where it is asked whether the flow is to account A&#39;s borrower  2 . If “yes”, POS(C) is augmented with the flow amount at step  299 . If not, POS(C) is decremented by the flow amount at step  300 . In either case, control is returned to step  296 . Note that the inner loop  296 - 300  is analogous to the loops in  FIGS. 27 and 28 . At step  301 , NPOS is augmented by the absolute value of POS(C) multiplied by “fixed rate C:N”, which converts to the notional instrument. The absolute value of POS(C) is used, because a negative position presents the same risk to the guaranteeing agent  5  as a positive position.  
         [0169]     Before we describe step  302 , let us define A and B, as those terms are used in step  302 . Note that “A” in step  302  is not the same as “account A”. A is the position of L, POS(L), multiplied by “fixed rate L:N”, which converts this position to the notional instrument. B is the position of Q, POS(Q), multiplied by “fixed rate Q:N”, which converts this to the notional instrument. The positions of L and Q are as calculated in the above loop  294 - 301 ; if L and Q were not subject to these notional limits, then A and B would be 0.  
         [0170]     In step  302 , computer  1  finds the minimum and maximum roots of F(X), where F(X) is defined in step  302 . The term “root” is that of conventional mathematical literature, i.e., a value of X that makes F(X) equal to 0. Let us define E to be equal to the absolute value of A plus B, plus NPOS, minus the absolute value of A, minus the absolute value of B, minus PMAXN. If E is greater than 0, then there are no roots. In that eventuality, we set the maximum excursion of the traded instrument L:Q, MAXEXC(L,Q), and the minimum excursion of the traded instrument L:Q, MINEXC(L,Q), to be equal to 0. If E is less than or equal to 0, the maximum root is the maximum of minus A and B, minus E/2; and the minimum root is the minimum of minus A and B, plus E/2. Now we are ready to go to step  303 .  
         [0171]     At step  303 , the maximum excursion of the traded instrument L:Q is set equal to the minimum of the previous version of the maximum excursion of the traded instrument L:Q and the maximum root multiplied by “fixed rate N:L”, which converts it to the lot instrument. Similarly, the minimum excursion of the traded instrument L:Q is set equal to the maximum of the previous version of the minimum excursion of the traded instrument L:Q and the minimum root multiplied by the same conversion factor, “fixed rate N:L”. The method terminates at step  304 .  
         [0172]      FIG. 32  illustrates how computer  1  calculates the notional volume limit, i.e., how computer  1  performs step  214  of  FIG. 26 . The method starts at step  311 . At step  312 , computer  1  retrieves the specified input maximum notional volume credit limit, VMAXN. This is a limit across all instruments in the account. At step  312 , the total volume, VOL, is also zeroed out. At step  313 , computer  1  looks for another unsettled flow of any instrument C in account A. Again, “another” is arbitrary. At step  314 , it is asked whether such another unsettled flow has been found. If “yes”, step  315  is executed; if “no”, step  316  is executed.  
         [0173]     Let R be the conversion factor “fixed rate C:N”, where C is the instrument that we are looping through currently. Then, step  315  sets VOL to be the previous VOL plus the quantity R times the flow amount. Step  313  is then entered into. At step  316 , X is set equal to VMAXN minus VOL. Again, X is the limit from just this flowchart. At step  317 , the maximum excursion of the traded instrument L:Q is set equal to the minimum of the previous value of the maximum excursion of the traded instrument L:Q and X times “fixed rate N:L”, i.e., we are converting from the notional instrument to the lot instrument. Similarly, the minimum excursion of the traded instrument L:Q is set equal to the maximum of the previous version of the minimum excursion of the traded instrument L:Q and minus X times the same conversion factor. The method ends at step  318 .  
         [0174]      FIG. 33  illustrates how computer  1  calculates an instrument position limit, i.e., how computer  1  performs step  216  of  FIG. 26 . This type of position limit differs from the previous position limit flowcharts ( FIGS. 27 and 28 ) in that the guaranteeing agent  5  is specifying that another agent  2  cannot trade any more than j L for Q, rather than the other agent  2  can trade no more than jL or jQ. This type of input credit limit is not as common as the ones described in  FIGS. 27 and 28 . If no agent  2  has specified this type of input credit limit, this flowchart  33  does not have to be executed. (Similarly, if no agent  2  has specified a certain other type of input credit limit, the flowchart corresponding to that credit limit does not have to be executed.) Both the L and the Q have to match in order for this flowchart  33  to be executed, unlike the flowcharts described in  FIGS. 27 and 28 .  
         [0175]     The method starts at step  321 . At step  322 , computer  1  looks up the specified maximum position credit limit for the traded instrument L:Q, PMAX(L,Q), and the specified minimum position credit limit for the traded instrument L:Q, PMIN(L,Q). In step  322 , the total position, POS, is also zeroed out. In step  323 , computer  1  looks for another unsettled flow pair with lot instrument L, quoted instrument Q, and account A. Again, “another” is arbitrary. At step  324 , it is asked whether such another unsettled flow pair has been found. If “no”, control passes to step  328 . If “yes”, control passes to step  325 , where it is asked whether the lot instrument flows to account A&#39;s borrower  2 . In other words, the calculation is done in terms of the lot instrument to begin with, so that we do not have to convert to the lot instrument at the end of the calculation. If the answer to this question is “yes”, step  326  is executed, where POS is incremented with the lot instrument flow amount. Control then passes to step  323 . If the answer to the question posed in step  325  is “no”, step  327  is executed, where POS is decremented by the lot instrument flow amount. Again, control then passes to step  323 . At step  328 , X is set equal to PMAX(L,Q) minus POS, and Y is set equal to PMIN(L,Q) minus POS. At step  329 , the maximum excursion of the traded instrument L:Q is set equal to the minimum of the previous version of the maximum excursion of the traded instrument L:Q and X; and the minimum excursion of the traded instrument L:Q is set equal to the maximum of the previous value of the minimum excursion of the traded instrument L:Q and Y. The method ends at step  330 .  
         [0176]      FIG. 34  illustrates how computer  1  calculates a traded instrument volume limit, i.e., how computer  1  performs step  218  of  FIG. 26 . This method is similar to the method described in  FIGS. 29 and 30 , except the limit is on the volume traded of L for Q, not a limit on the volume of L or Q individually. The method starts at step  341 . In step  342 , computer  1  retrieves the specified maximum volume input credit limit for the traded instrument L:Q, VMAX(L,Q). Also in step  342 , the total volume VOL is zeroed out. In step  343 , computer  1  looks for another unsettled flow pair with lot instrument L, quoted instrument Q, and account A. Again, “another” is arbitrary.  
         [0177]     At step  344 , it is asked whether such another unsettled flow pair has been found. If “no”, control passes to step  346 . If “yes”, control passes to step  345 , where VOL is augmented by the lot instrument flow amount. The calculation is done in the lot instrument, so that we do not have to convert to the lot instrument at the end; and it makes the calculation more stable, because we don&#39;t have to worry about fluctuating rates. Control is then passed to step  343 . At step  346 , X is set equal to VMAX(L,Q) minus VOL. At step  347 , the maximum excursion of the traded instrument L:Q is set equal to the minimum of the previous version of the maximum excursion of the traded instrument L:Q and X. Similarly, the minimum excursion of the traded instrument L:Q is set equal to the maximum of the previous value of the minimum excursion of the traded instrument L:Q and minus X. The method stops at step  348 .  
         [0178]      FIG. 35  illustrates the reporting by computer  1  of single-hop trades. This method is executed after a match has been made, i.e., after a bid or offer has been taken by a counterparty  2 . The method of  FIG. 35  can be done either in real time or in batch mode (i.e., combined with the reporting of other trades). In  FIG. 35 , L is the lot instrument, Q is the quoted instrument, B is the agent  2  who is buying L, S is the agent  2  who is selling L, P is the trade price, FL is the amount of L bought and sold, FQ is P times FL, i.e., the counter-amount in terms of instrument Q, and T is the settlement date and time.  
         [0179]     The method starts at step  351 . At step  352 , central computer  1  issues an electronic deal ticket  353  to an auditor. The auditor is a trusted third party, e.g., an accounting firm. Ticket  353  has a plaintext portion and an encrypted portion. The plaintext gives the ticket ID, and the time and date that the ticket  353  is generated. The encrypted portion states that agent B bought FL for FQ from agent S for settlement at T. Deal ticket  353  is digitally signed by central computer  1  for authentication purposes, and encrypted by central computer  1  in a way that the auditor can decrypt the message but central computer  1  cannot decrypt the message. This is done for reasons of privacy, and can be accomplished by computer  1  encrypting the message using the public key of the auditor in a scheme using public key cryptography.  
         [0180]     At step  354 , computer  1  issues an “in” flow ticket  355  to buyer B and to the auditor. Flow ticket  355  contains a plaintext portion and an encrypted portion. The plaintext gives the ticket ID, the time and date the ticket  355  is generated, and the name of agent B. The encrypted portion states that you, agent B, bought F L  for F Q  from counterparty S for settlement at T. Ticket  355  is digitally signed by computer  1  and encrypted in such a way that it may be decrypted only by agent B and by the auditor, not by computer  1 . Two different encryptions are done, one for agent B and one for the auditor.  
         [0181]     At step  356 , computer  1  issues an “out” flow ticket  357  to seller S and to the auditor. Out flow ticket  357  contains a plaintext portion and an encrypted portion. The plaintext gives the ticket ID, the time and date of issuance, and the name of agent S. The encrypted portion states that you, agent S, sold F L  for F Q  to counterparty B for settlement at T. Ticket  357  is digitally signed by computer  1  and encrypted only to agent S and to the auditor, not to computer  1 . Two different encryptions are used, one to agent S and one to the auditor.  
         [0182]     Tickets  353 ,  355 , and  357  can include the digital identity of the individual within the agent  2  whose smartcard was plugged into the agent&#39;s computer when the transaction was made. The method ends at step  358 .  
         [0183]      FIG. 36  illustrates how computer  1  electronically reports a multi-hop deal. This method is performed after the match has been made and can be done either in real time or in batch mode. Agents B and S do not know each other, as they know the identities of just their nearest neighboring agents  2 . The notation for this flowchart is identical to that for  FIG. 35 , except that B is the ultimate buyer of L and S is the ultimate seller of L.  
         [0184]     The method begins at step  361 . At step  362 , computer  1  issues deal ticket  363  to the auditor. Ticket  363  contains a plaintext portion and an encrypted portion. Ticket  363  is digitally signed by computer  1  and encrypted only to the auditor. The encrypted portion states that agent B bought F L  for F Q  from agent S for settlement at T, and that the deal was fulfilled by multiple direct trades in D, the directed deal fulfillment graph, i.e., the type of graph that is illustrated in  FIG. 11 . In other words, the auditor knows every agent  2  in the chain.  
         [0185]     At step  364 , computer  1  looks for the next unprocessed agent V in graph D. Again, “next” is arbitrary. At step  365 , it is asked whether such an unprocessed agent V has been found. If not, the method stops at step  366 . If the answer is “yes”, node loop  370  is entered into. For agent V, this node loop examines the set Ev of directed edges  3  in D which have agent V as either a source or destination. Each edge  3  has an amount F that is greater than zero and less than or equal to F L . Note that this verification process is for illustration only; there would not be a match if these constraints were not satisfied. At step  367 , it is asked whether agent V is the ultimate buyer B of the deal. If “no”, control is passed to step  368 . If “yes”, control is passed to step  371 .  
         [0186]     At step  368 , it is asked whether agent V is the ultimate seller S of the deal. If “no”, control is passed to step  369 . If “yes”, control is passed to step  372 . At step  369 , computer  1  concludes that agent V is an incidental participant in the deal, i.e., a middleman  5 . Control is then passed to step  373 , which verifies that the sum of the edge  3  amounts having agent V as a source equals the sum of the edge amounts  3  having agent V as a destination. Sums are used because that agent  5  could have several edges  3  in and out. Therefore, it is known that agent V has no net market position change. Control is then passed to step  376 . At step  372 , it is verified that agent V is the source node  2  (as opposed to the destination node) of all edges  3  in E V . In step  375 , it is verified that edge  3  amounts in E V  sum to F L , the net amount sold. Control is then passed to step  376 .  
         [0187]     In step  371 , it is verified that agent V is the destination node  2  (as opposed to the source node) of all edges  3  in E V . At step  374 , it is verified that edge  3  amounts in E V  sum to F L , the net amount bought. Control is then passed to step  376 , where computer  1  looks for the next unprocessed edge in E V  corresponding to account A. Steps  376 - 382  constitute an edge loop. Account A is any account held by or extended to counterparty X. Counterparty X is the counterparty  2  to agent V for that edge  3 . The edge  3  has to have some amount F, where F is greater than 0 and less than or equal to F L , and an implicit counter-amount F times P; otherwise, there would be no way to clear the trade. Again, “next” in step  376  is arbitrary. Control is then passed to step  382 .  
         [0188]     At step  382 , it is asked whether such a next unprocessed edge  3  has been found. If not, control is passed to step  364 . If “yes”, control is passed to step  381 , where it is asked whether agent V is the destination node  2  for this edge  3 . If “yes”, then step  380  is executed. If “no”, then by definition, agent V is the source node  2  for this edge  3 , and step  379  is executed. Control is passed to step  376  after either of step  379  or  380  is executed.  
         [0189]     At step  380 , computer  1  reports an “in” flow ticket  377  to agent V, because the lot currency is flowing in to agent V. Flow ticket  377  contains a plaintext portion and an encrypted portion. The plaintext includes the ticket ID, the time and date of issuance, and the name of agent V. The encrypted portion states that you, agent V, bought F of L for F times P of Q from counterparty X for settlement at T. In this case, counterparty X is just the immediate neighbor  2  to agent V, preserving anonymity. Ticket  377  is digitally signed by computer  1  and encrypted by computer  1  only to agent V and to the auditor, not to computer  1 . Two encryptions are performed, one to agent V and one to the auditor.  
         [0190]     At step  379 , computer  1  generates an “out” flow ticket  378  to agent V. Ticket  378  contains a plaintext portion and an encrypted portion. The plaintext includes the ticket ID, the time and date of issuance, and the name of agent V. The encrypted portion states that you, agent V, sold F of L for F times P of Q to counterparty X for settlement at T. Again, counterparty X is just the immediate neighbor  2  to agent V, preserving anonymity. Flow ticket  378  is digitally signed by computer  1  and encrypted by computer  1  only to agent V and to the auditor, not to computer  1 . Two encryptions are performed, one to agent V and one to the auditor.  
         [0191]     Tickets  363 ,  377 , and  378  can include the digital identity of the individual within agent  2  whose smartcard was plugged into the agent&#39;s terminal when the transaction was made.  
         [0192]     A further aspect of the invention can be implemented using the above desribed architecture as will be readily apparent to those of ordinary skill in the art, and relates to proximity measures.  
         [0193]     As described in previously filed Provisional Application Ser. No. 60/540,392 entitled “Single-period Auctions Network Decentralised Trading System and Method” and in concurrently filed U.S. application Ser. No. ______ (Attorney Docket No. 0889-003) entitled “Single-Period Auctions Network Decentralized Trading System and Method” of the same inventor, the disclosures of both being specifically incorporated by reference herein, a “network of credit lines” is comprised of lines of credit extended by “credit sources” (typically financial institutions, and other nodes allowed by the architecture to extend credit) to credit sinks (their “customers”), and lines of credit in place between various credit sources. This network of credit can be thought of as a directed graph. If a credit source A extends credit to another node B that is also a credit source in its own right, then, from the frame of reference of the credit extending node A, node B is a credit sink. The arguments carry forward as credit sources have a dual role from time to time, depending on the underlying network topology (without loss of generality, a financial institution may regard another financial institution as its customer from its frame of reference, and vice-versa).  
         [0194]     Directed edges between nodes in the graph denote the direction of credit extension. If a directed edge exists from node A to node B, then B has been extended credit by A. Any action or information that A allows sink B to communicate to A, and therefrom (if allowed by A), to communicate to another sink, C, sink B is communicating this information to sink C “in the name of” source A. In other words, from the frame of reference of C, information is only being relayed to it by A, whereas from the frame of reference of node B, B is relaying information only to A. By the rules of credit extension, A in this case is representing to C that whatever it is relaying to it, it is the obligor for any liabilities for actions that A allows C to perform on the basis of information that A relays to C, and conversely, A is relaying to B that A is the obligor of any actions A has agreed with B that B is able to perform on the basis of any information sent to A by B.  
         [0195]     Associated with each edge between a source and a sink, are rules that the source sets as to type of information that a source may receive from the sink, the type of information that a sink may send to the source and what happens to the information exchanged between the two. This information includes, among other things, the type of goods that a source agrees can be traded with the sink. The rules contain a matrix with a “capacity column” that sets the capacity of each edge with respect to each row denoting capacity of the edge with respect to flow for different commodities that a source wishes to trade, and rules relating to how flow is affected for one particular instrument pair by a sink trading another particular instrument pair.  
         [0196]     The notion of “network dealing architecture” is defined as a system that enables a source, having set all rules of interaction between itself and its sinks in regards to exchange of particular instrument-pairs, to provide a venue for its sinks to be able to exchange the instrument-pairs with the source, or, exchange instrument-pairs in the name of the source, with each other.  
         [0197]     As discussed in co-pending provisional application (Attorney Docket No. 0889-001), network dealing enables “linking” of venues between sources. Should a source A extend a line of credit to an entity B that is a source in its own right, then, entity B may choose to allow any information relayed to it by A to be relayed, according to its&#39; own rules that B may set, to sinks of source B. Furthermore, suppose that from the frame of reference of node B, C is a sink and also a source in its own right, with its own sinks (note: C regards B as its&#39; sink), with C setting its&#39; own rules how information is to be relayed from its sink B to its&#39; other sinks.  
         [0198]     The network dealing architecture enables information to be passed from a sink of source A, translated according to rules A sets, relayed to its&#39; sinks, according to rules A sets for each sink, including sink B. Sink B, being a source in its&#39; own right, translates information received by its sink A, and passes the information to its&#39; sinks, according to rules it sets to its own sinks, including sink C. Carrying forward, sinks of source C are able to act on information they receive, which has been translated by C and act on it.  
         [0199]     Ultimately, trading between sinks of source A and source C is facilitated for a) instruments at, b) prices and up to, c) amounts that each A, B, and C have set and modified along the way, on each, a), b) and c).  
         [0200]     Network dealing enables arguments above to carry forward for any arbitrary network topology of any set of sources and sinks.  
         [0201]     Consequently, in any arbitrary network topology, each sink of each source is presented with a custom “heterogeneous” limit order book, giving each sink a “view” of the market that its source allows it to have, and be able to trade on instruments it has access to trade, at prices as relayed by the sink, up to sizes that a sink is allowed to see, which is a function of the rules governing credit that a source sets.  
         [0202]     The power and the beauty of the network dealing architecture is that not only does it allow for sources to vary their rules-matrices, in real time, but that the effects of one source changing a rule in one part of the network are instantaneously (and computationally feasibly) reflected onto the limit order books of all sources and all sinks in the network. The architecture keeps all limit order books for all parties “true” and “dealable” at all times.  
         [0203]     Facilitating flows in a “breathing network” scenario allows for a source to link into the network on-the-fly, according to rules it sets and furthermore, allows each source to monitor and limit its&#39; delivery risks exposure against its counterparties, while, at the same time, trading by sinks is done with sinks not having any increased counterparty exposure since they only deal with known parties who guarantee delivery in return.  
         [0204]     In accordance with the invention, there are provided further generalised network flows and proximity measures, as discussed hereafter.  
         [0205]     One underlying assumption in the standard network-dealing model is that the set of rules that a source sets for a sink specify which instrument pairs are available to which sink to transact on via customised heterogeneous limit order books, reflecting relative credit usage of each sink and credit rules that a source sets for its&#39; sinks. In other words, a sink has only the ability to transact in those item-pairs that are offered by a source, or passed in its name to its&#39; sinks. Transactions in terms of which pairs of items are pre-agreed on by the virtue of a custom limit order book containing only bids and offers on one item in exchange for another item, with the items being fixed. Should a source wish to transact in another pair of items, it has to have access enabled to transact in that pair and therefore access to a limit order book for that pair. In other words, the standard network dealing model enables each source to open access for a sink in trading in several rooms (order books). A presence in a room signifies the ability of the person to trade a pair of items for which that room is set up for, with parties allowed by their source to transact in that room. The notion of limit order books signifying the exchange of a particular pair of items is deeply indebted in the methods by which online dealing takes place, from electronic exchanges to the network dealing model described herein.  
         [0206]     The second underlying assumption in the standard network dealing model is that a sink that is unable to act as a source in its own right (i.e. an entity not allowed to extend lines of credit to others) cannot specify any rules in regards to how its bids and offers on an item are disseminated throughout the network in the name of its source.  
         [0207]     In accordance with the invention, the network dealing model is extended as follows. A sink A is allowed to take an item x and define a set of rules it deems define specific properties of x important to A, i.e., P_A(x). The system enables A to relay to any source B one or the other or both pieces of information, e.g., that it wishes to purchase or sell x, together with the property of x is deems important, i.e., P_A(x). The system allows for source B to view x containing a different set of important properties, as may be important to B, i.e., P_B(x). The system allows for what is important for A to be different from what is important to B. The system also allows A to allow or not allow B to view what properties A considers important in describing x. B may use its set of properties, i.e., P_B(x), along with A&#39;s set of properties, i.e., P_A(x), if A allows B to view this information. B may also take into account the fact that A is not allowing it to see P_A(x), and A would know this might be the case. Thus, a proper discounting of informational asymmetry between the two agents may be facilitated to feed into the credit engine for that source, and value how much credit A uses up with B in order for B to pass x along to its other sources.  
         [0208]     If A chooses not to reveal x, but only P_A(x), B is still able to draw inferences P_B( P_A(x)) and infer credit usage in valuating the unknown item.  
         [0209]     The architecture, then, enables A to communicate to B that it wishes to buy or sell item x or that it wishes to buy or sell an item by giving just the property of x that A deems important, P_A(x).  
         [0210]     The system enables B to apply its own mapping to relay to its other sinks that it extended a line of credit, that it wishes to sell or buy either or both item x or some other item matching just the property P_B(x) or, most significantly, P_B(P_A(x)), i.e., some item containing properties B is willing to counter to A given the properties of the item that A wishes to receive from B.  
         [0211]     The architecture enables B to send to its sink, say C, either x and/or P_B(x) and/or P_B(P_A(x)), or indeed to specify that given it is relaying information to a specific sink C, that this information be a function of the type of sink to which the information is being relayed to by B.  
         [0212]     The upshot of this architecture is that a party A may seek to obtain (or sell) either a specific item x, or may use the architecture to attempt to transact in not necessarily a specific item but some item possessing certain properties only that it is interested in. Some of the properties specified may be made mandatory. Others may be prioritized in order of importance. For example, not certain financial instrument, but an instrument of such-and-such maturity, derived from such-and-such basket of underlying class of instruments, with certain historical performance measures, from a certain region only and so on, limited only by the richness of the set of properties A defines x with, and the information B relays about A&#39;s desire to its other sinks and so on through the network.  
         [0213]     The architecture then translates information relayed by A into information acceptable by its credit extending agent, B, and passes it on in a manner consistent with B&#39;s utility onto its sinks, which, ones that are sources in turn, may pass them onto their own sinks and so on throughout the network.  
         [0214]     The network itself is also endowed with two pieces of intelligence. A first piece is an objective function it defines to metrise the space of properties relayed through the channels in order to maximise the likelihood of a match of properties or items (the “proximity metric”). A second is the constraint function set by each source in the network defining the manner in which it chooses to relay information sent to it, through it, onto its other sinks.  
         [0215]     These are just some examples of algorithms AA may use to try to maximise the probability that it is the agent that ultimately “makes the sale”, i.e., given what information it receives about what agents want, and what other agents are looking for, it can select some criteria by which it decides what information regarding what agents are selling it passes to agents that are interested in buying.  
         [0216]     The system allows for an arbitrary specification of the proximity measure. Among several proximity measures is that one is a function of past matches of bids and offers in the network, sequences of iterative refinements to the process generating proximity measures, converging towards an optimal proximity measure, all this still in the presence of asymmetric descriptive information.  
         [0217]     The iterative metric essentially infers a meta-property of x, PP(x), whether x is known or only specified by a sink as P_A(x). PP(x) is a function of the likelihood of a match being made in the past by P_A(x) being relayed, over all x, and what distance PP(x) imposes on the space of all P_A(x), over all A and over all x transacted in the past or given as an initial condition. Essentially, PP(x) is the property that the network decides is important about x in order to facilitate a match between a sink A and other sinks and sources in the network.  
         [0218]     The proximity metric uses PP(x) to sort all counteroffers by likelihood of them being accepted by the sink A which made the original offer. A is presented with its proximity-special order books where it may choose which offer best suits its original list of important properties regarding x and/or P_A(x) and conducts a trade. Counteroffer representing an item that A chooses to transact may or may not be the first item in the proximity-special order books presented to A by the system based on PP(x). In either case, the System records the actual match that A chose and proceeds to refine PP(x) on the basis of x, P_A(x), and all other P_B(x), over all sinks B that replied to A&#39;s request. PP(x) is refined to maximize the probability of items in its subsequent sorted lists on subsequent trades, being presented as first choices. In other words, the system will attempt to refine PP(x) to be such that sinks will choose the item that PP(x) presents as its top choice, as their top choice. Note that A may choose to let the System, based on PP(x) and any additional input, perform a match automatically.  
         [0219]     To further illustrate the following, are specific examples of how the rules may be implemented to achieve maximum mapping on a global basis.  
       EXAMPLE 1  
       [0220]     1. Let sink A be allowed to take an item x and define a set of rules it deems define specific properties of x important to A, i.e., P_A(x). The system enables A to relay to any source B one or the other or both pieces of information, e.g., that it wishes to purchase or sell x, together with the property of x is deems important, i.e., P_A(x). The system allows for source B to view x containing a different set of important properties, as may be important to B, i.e., P_B(x). The system allows for what is important for A to be different from what is important to B. The system also allows A to allow or not allow B to view what properties A considers important in describing x. B may use its set of properties, i.e., P_B(x), along with A&#39;s set of properties, i.e., P_A(x), if A allows B to view this information. B may also take into account the fact that A is not allowing it to see P_A(x), and A would know this might be the case. Thus, a proper discounting of informational asymmetry between the two agents may be facilitated to feed into the credit engine for that source, and value how much credit A uses up with B in order for B to pass x along to its other sources.  
         [0221]     2. Let it also be that if A chooses not to reveal x, but only P_A(x), B is still able to draw inferences P_B(P_A(x)) and infer credit usage in valuating the unknown item.  
         [0222]     3. Let I_x be a set of information I about an item x received by an agent AA. This information can be arbitrary, from simple numbers specifying price or quantity of x, to linguistic description of x, photos, contracts, third party opinions of x, literally anything someone deemed relevant to describe some item x. x may be an item, a contract, an entity, a relationship between two parties, literally anything that can be spoken about and described by one person to another or one machine to another using a language.  
         [0223]     3. Let then P_AA(1×) be the set of all variables (properties) that some agent AA sets to describe properties regarding some set of information it receives, Ix about some item x.  
         [0224]     4. The set Ix, information about item x, may include for example i) x itself described in detail, ii) description of x by another agent which may or may not coincide exactly with x, but which some other agent deemed relevant to it to describe x in detail. Therefore, Ix may itself be a collection of properties of x deemed relevant by other agents.  
         [0225]     5. The invention allows any agent to specify several choices of “proximity metrics” it wishes to use to map the set of information it receives about an item, 1× from the network and what it relays to the network about Ix, P_AA(Ix).  
         [0226]     6. Examples include but are not limited to the following set of mappings: 
        Delta metric: AA sets that it is willing to receive offers if and only if offers possess at least all properties AA has deemed relevant about the item. I.e. AA will consider receiving information from some agent BB, P_BB(Ix) if and only if P_BB(Ix) encompasses (includes) P_AA(Ix).     Restricted Delta metric: AA sets that it is willing to receive offers if and only if offers posses exactly and only properties AA has deemed relevant about the item, i.e. AA will receive P_BB(Ix) if and only if P —BB(Ix)=P _AA(Ix).     Open metric: AA may set that it is willing to receive and pass on any and all information from any agent to any other agent it is connected to.     Personal Max-likelihood metric: Given a historical sequence of information AA received about items from other agents, and what matches were made by the ultimate buyer and seller where AA was one of the intermediaries, AA may choose to select an algorithm that maximises the likelihood that whatever information (items or their property) AA receives from agents and what information AA relays to agents about available items or their property, maximises the probability of a match, between buyers and sellers. The criteria may include, but are not limited to: historical matches, Bayesian refinements and heuristics.     Network Max-likelihood: Network Max-likelihood differs from Personal Max-likelihood in that agents are allowed to ‘post’ to the network their own personal sets of information that they used to create a match between buyers and sellers. The network then aggregates this information and comes up with a global max-likelihood metric: Given a historical sequence of information all agents received about items from other agents, and what matches were made by the ultimate buyer and seller, the network max-likelihood algorithm maximises the likelihood that whatever information (items or their property) any agent receives from agents it is connected to and what information any agent relays to agents it is connected to about available items or their property, maximises the probability of a match, between buyers and sellers. The criteria may include, but are not limited to: historical matches, Bayesian refinements and heuristics.        
 
         [0232]     The Example set forth above illustrates some version of algorithms AA which one may use to try to maximise the probability that it is the agent that ultimately “makes the sale”, i.e. given what information it receives about what agents want, and what other agents are looking for, it can select some criteria by which it decides what information regarding what agents are selling it passes to agents that are interested in buying.  
       EXAMPLE 2  
       [0233]     In a specific layperson example, consider that a buyer wishes to buy a Mont Blanc pen, which is black, fourteen years old and for twenty dollars. These rules may be set by the request, with highest priority given to “Mont Blanc”. A party receiving the information may retransmit the request but specify only that the pen need be a Mont Blanc pen, with a price limit of thirty dollars. Alternatively, the requirement that it be a Mont Blanc may be mandatory so that no replies are accepted for non-Mont Blanc tenders. Given this, a reply by a third party may tender a green Mont Blanc pen for twenty five dollars and it is retransmitted to the first party. Since “Mont Blanc” is highest in priority, this trade may be accepted.  
         [0234]     The above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. The scope of the invention is to be limited only by the following claims. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the spirit and scope of the present invention.
A method and system provide for conducting of trades. A request is transmitted from one party, about an item the party is willing to trade. Rules are specified about what will be acceptable. Responses are received from other parties concerning requests which are responsive to the rules. A trade is conducted with one or more parties responding in accordance with the rules.