A Parallel Interval-Based Constraint Language: Implementation and Performance Analysis

Abstract

This paper presents the design and implementation of a non-deterministic constraint programming language based on interval variables (integer or floating point intervals) on shared-memory multiprocessing computers. The non-deterministic constructs in the language are the choice and split statements. Each processor narrows the constraints encountered along the path of the execution tree. Whenever a solution is found, the processor is re-used in exploring other branches of the execution tree. Similarly, a failed narrowing frees the corresponding processor to be re-used with a subsequent split or choice statements. A meta-level interpreter is presented to describe the execution behavior of the language. The behavior of the meta-level interpreter is also approximated by considering strings generated by a context-free grammar and derivable from the interpreter rules. A novel approach presented here is an attempt to determine the average case speed up by generating uniform random strings us..