INTRODUCTION TO GUARDED HORN CLAUSES.

This paper informally introduces the programming language Guarded Horn Clauses (GHC) through program examples. GHC is a parallel programming language devised from investigation of the basic framework and practice of logic programming. It introduces the guard construct with simple semantics into logic programming to express interacting processes. A GHC program naturally expresses parallelism inherent in the original problem. The simple and uniform framework of GHC should be far easier to understand than the constructs of conventional parallel programming languages. We explain GHC in comparison with Prolog, the best-known logic programming language.