Deduction graphs: an algorithm and applications

Abstract

A deduction graph (DG) for logically deducing a new functional dependency (FD) or function-free Horn formula (extended from Horn clauses) from a subset of a given FDs or function-free headed Horn clauses in a relational database or rule-based expert systems is defined. An algorithm with a polynomial time complexity for constructing a DG based on a number of rules is designed. Applications of DGs to relational databases, rule-based expert systems, logic programming, and artificial intelligence are investigated. In addition to graphically solving the inference problem by DGs, many logic queries can be answered by DGs with substitutions for unifying expressions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>