A KIND OF LOGICAL COMPILATION FOR KNOWLEDGE BASES

The forward chaining algorithm is perhaps the best-known algorithm in expert systems. However, it is not complete because it cannot compute the two-valued consequence literals of a propositional knowledge base (i.e. set of rules) with negations. If the user wants to compute them, he must use a particular algorithm, which often takes much time. We p ropose a compilation system for knowledge bases, which we call logical compilation, which allows us to compute the two-valued consequence li terals of a knowledge base (i.e. set of rules) using a forward chainin g on the compiled base with any extensional knowledge base (i.e. set o f basic facts) added. We also use this compilation in a wide propositi onal calculus and solve the ''or'' problem in rule conclusion. We pres ent several methods with their benefits to make this compilation and w e give properties on knowledge bases to avoid this compilation. Finall y, we give a theorem which defines incremental compilation.