HIGH-LEVEL PETRI-NET MODEL OF LOGIC PROGRAM WITH NEGATION

The formalism of nonmonotonic reasoning has been integrated into logic programming to define semantics for logic program with negation. Beca use a Petri net provides a uniform model for both the logic of knowled ge and the control of inference, the class of high-level Petri nets ca lled predicate/transition nets (PrT-nets) has been employed to study p roduction rule based expert systems and Horn clause logic programs. He re we show that a PrT-net can implement the nonmonotonicity associated with a logic program with negation as well as the monotonicity of Hor n clause logic program. In particular, we define a semantics for a nor mal logic program and implement it with PrT-net. We demonstrate that i n the presence of inconsistency in a normal logic program, the semanti cs still works well by deducing meaningful answers. The variations and potential applications of the PrT-net are also addressed here.