An OR-parallel and restricted AND-parallel nonbacktracking Prolog execution model

A nonbacktracking restricted AND-parallel, and OR-parallel Prolog execution model, PPEM, is introduced. The execution monitor of PPEM, automatically generates the solution tree incrementally for a given program, using restricted AND-parallelism. A new representation, the Active Processes Tree, used for tracing the parallel execution of Prolog programs, is introduced. A set- based algorithm controls restricted AND-parallel execution of and-terms in PPEM. All solutions are searched in trying an and- term. If an and-term fails, the subtree of the solution tree emanating from its parent is discarded. No processes are created for facts, and rules with single and-terms. The execution mechanism of PPEM is introduced, and illustrated with examples.