Algernon—a tractable system for knowledge-representation

Abstract

Access-Limited Logic (ALL) is a theory of knowledge representation which formalizes the access limitations inherent in a network structured knowledge-base. Where a deductive method such as resolution would retrieve all assertions that satisfy a given pattern, an access-limited logic retrieves only those assertions reachable by following an available access path. The time complexity of inference in ALL is a polynomial function of the size of the accessible portion of the knowledge-base, rather than an exponential function of the size of the entire knowledge-base (as in much past work). Access-Limited Logic, though incomplete, still has a well defined semantics and a weakened form of completeness, Socratic Completeness, which guarantees that for any fact which is a logical consequence of the knowledge-base, there is a series of preliminary queries and assumptions after which a query of the fact will succeed.