A multisystem-based parallel-interpreter of logic programs with restricted AND-parallelism and OR-parallelism

Two kinds of parallelisms arise when interpreting a logic program with a parallel architecture: OR-parallelism and AND-parallelism. Our goal is to present an interpreter that can exploit restricted AND-parallelism, combined with OR-parallelism. The method relies on a different scanning of the search space and works on a new concept that we call multisystem. It is shown that the proposed interpreter outperforms previously classical interpreters, avoiding the mentioned combinatorial explosion of search paths of the OR-parallel models in many problems. The proposed approach presents some good characteristics: all the known techniques to exploit restricted AND-parallelism can be used with it; the number of search paths could be exponentially smaller than that needed by existing interpreters (using OR-parallelism); regarding the total running time, the small number of search paths created is a crucial factor because it avoids serialising their execution; the reduction in the required memory space in the proposed interpreter (even exponential in a best case) follows from the fact that a multisystem is equivalent to a set of multiple bindings but represented in a compact and hierarchical way