Logic Programming Research

And-Or Parallel Prolog: A Recomputation Based Approach

Journal of New Generation Computing Vol.11(3,4), June 1993, pp. 298-321

Gopal Gupta, Manuel Hermenegildo, Vitor Santos Costa

We argue that in order to exploit both Independent And- and Or-parallelism in Prolog programs there is advantage in recomputing some of the independent goals, as opposed to all their solutions being reused. We present an abstract model, called the Composition-Tree, for representing and-or parallelism in Prolog Programs. The Composition-tree closely mirrors sequential Prolog execution by recomputing some independent goals rather than fully re-using them. We also outline two environment representation techniques for And-Or parallel execution of Prolog based on the Composition-tree model abstraction. We argue that these techniques have advantages over earlier proposals for exploiting and-or parallelism in Prolog.

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