26. A non-transitory computer readable medium storing one or more sequences of instructions for causing an ontology system to provide enhanced search capability, wherein said ontology system maintains information in the form of a plurality of ontologies, wherein each of said plurality of ontologies contains a corresponding plurality of nodes and a corresponding plurality of edges, some of said plurality of edges being of a corresponding one of a plurality of relationship types between a corresponding pair of said plurality of nodes, wherein the relationship type of an edge indicates the specific relation represented by the edge, wherein execution of said one or more sequences of instructions by one or more processors contained in said ontology system causes said ontology system to perform the actions of: receiving a search request specifying a set of nodes and a set of edges of interest, said search request further specifying a corresponding one of a set of relationship types for each of said set of edges of interest, wherein said set of relationship types is contained in said plurality of relationship types, wherein said received search request contains express data which explicitly identifies each of said set of nodes of interest, said set of edges of interest and said set of relationship types; determining a set of ontologies matching said search request based on said set of nodes and said set of edges of interest, wherein said set of ontologies is contained in said plurality of ontologies, wherein said set of ontologies contains a first ontology and a second ontology, said first ontology and said second ontology respectively containing a first edge and a second edge, wherein both of said first edge and said second edge are between a same pair of nodes of said first ontology and said second ontology, wherein both of said same pair of nodes are contained in said set of nodes received in said search request, wherein said first edge in said first ontology is of a first relationship type matching the corresponding relationship type explicitly identified for a first edge of interest in said search request, wherein said first edge of interest is also between said same pair of nodes in said search request, wherein said second edge in said second ontology is not of said first relationship type; computing a match score for each of said set of ontologies, wherein a first match score and a second match score are respectively computed for said first ontology and said second ontology, wherein said first edge contributes more to said first match score than said second edge contributes to said second match score in view of said first edge being of said first relationship type in said first ontology, and said second edge not being of said first relationship type in said second ontology, rank said set of ontologies according to the computed match scores; and send a data indicating said set of ontologies and corresponding ranks as a result of said search request.
30. The non-transitory computer readable medium of claim 26 , wherein said first pair of nodes contains a first node and a second node, wherein said set of ontologies contains a third ontology having a third edge between said first node and a third node, wherein said third node is not contained in said set of nodes but said third edge is of said first relationship type to constitute a half edge in relation to said first edge, wherein said computing computes a third match score for said third ontology, wherein said third edge contributes less to said third match score than said first edge contributes to said first match score.