Logical inference of clauses based on Petri net models

This paper extends the logical inference of Horn clauses in Petri net models to cover a large class of non-Horn clauses. Based on four-valued logic and the conflict transition concept, we show how the Petri net model for this class of non-Horn clauses can be constructed. The clause inference is solved by the T-invariant method or the fixpoint of markings. Both forward and backward inference can be used in our model. It is further shown that these techniques are efficient for the common classes of monotonic reasoning. © 1998 John Wiley & Sons, Inc.