Towards a complete framework for parallel implementation of logic languages: the data parallel implementation of SEL

Abstract

Although logic languages, due to their non-declarative nature, are widely proclaimed to be conducive in theory to parallel implementation, in fact there appears to be insufficient practical evidence to stimulate further developments in this field. The paper puts forward various complications which arise in assuming a solely process parallel approach as a possible explanation for this situation. As an alternative, data parallelism is posited as an underutilized forte of logic programming. The paper illustrates a data parallel implementation of a particular language called SEL which is based on sets. Thus, SEL (set equational language) is introduced as an example of logic language which lends itself to an efficient data parallel implementation. The strategy of this implementation assumes an abstract machine called SAM (set-oriented abstract machine) which is based on the WAM (Warren abstract machine). SAM serves as an intermediary between the SEL language and the target machine for the implementation, the Connection Machine. Finally, some preliminary benchmarks are presented.