Complete and efficient methods for supporting side-effects and cuts in And-Or parallel Prolog

Abstract

Practical Prolog programs usually contain extralogical features like cuts, side-effects, and database manipulating predicates. It is noted that, in order to exploit implicit parallelism from real applications, a parallel logic programming system should necessarily support these features. How Prolog's extralogical features can be supported in an And-Or parallel logic programming system is discussed. It is shown that to support extralogical features an And-Or parallel logic programming system should recompute the solutions to independent goals instead of sharing them. An abstraction called the composition tree for representing And-Or parallel execution with recomputation is described. The notion of 'local-leftmostness' in the composition tree is introduced and used for deriving complete and efficient methods for supporting extralogical predicates in And-Or parallel logic programming systems based on the composition tree abstraction. >