1. In a computer system, a method of performing distributed computations, the steps of the method performed by said computer system comprising: providing cooperating agents to perform each distributed computation, each agent having an associated set of events representing state transitions among a predefined set of states, each said event having a truth value that said agent changes while performing said distributed computation, each agent further having means for sending event value notifications to other ones of said agents when said agent changes said truth value of any said event; storing in a computer memory associated with each agent a local knowledge database, said local knowledge database including data representing conditions for changing the truth value of local events, comprising events in said each agent and data representing conditions for changing the truth value of external events, comprising events in other ones of said agents, each of said conditions being represented in said local knowledge database as a boolean expression of the truth values of specified ones of said events in specified ones of said agents; said local knowledge database further storing data representing truth values for said local and external events known to said each agent; wherein said data representing said known truth values for at least a plurality of said local and external events is initialized to represent that said truth values are Undefined; performing each distributed computation with said agents provided for that distributed computation, including: whenever any one of said agents changes the truth value of any one of said local events, said one agent identifying from said conditions represented in said one agent's associated local knowledge database (A) those of said external events whose condition depends on said one local event, (B) for each identified external event, other ones of said local events, if any, upon which said external events' conditions depend, and (C) the truth values of said other local events; evaluating said condition for each said identified external event to generate a truth value for said evaluated condition; and sending notifications of said one local event and said other local events from said one agent to said agent associated with each said identified external event only when the evaluated condition associated with each said identified external event has a truth value other than an Undefined truth value.