Delta Prolog: A distributed backtracking extension with events

Abstract

We present Delta Prolog, a distributed logic programming language that extends Prolog to include AND-parallelism (in a single processor or across a network of processors), interprocess communication via message passing with two-way pattern matching, interprocess synchronization with simultaneous message passing, and distributed backtracking among a family of processes. The extension is achieved, at the language level, by just two additional types of goals — events and splits. The implementation is written part in Prolog and part in C, with a small number of core primitives, to help portability. It is still experimental and expected to evolve. In this work we present the language's distinguishing features, describe its semantics, exhibit programs and analyse their behaviour, examine the implementation, and mention conclusions, advantages of the approach and the next developments.