Finite failures and partial computations in concurrent logic languages

Abstract

This paper investigates some semantic properties of concurrent logic languages. Concurrent logic languages with a commit operator differ from pure logic languages in the finite failure set. Since the new finite failure set depends on the computation rule, we define an operational semantics based on a parallel computation rule and a fair search rule. Failures with a parallel computation rule are shown to be strongly related to partial computed answer substitutions. The set of partial computed answer substitutions and the set of finite failures are defined as the least fixpoint of a transformation on pairs of interpretations.