Conjunctive-query containment and constraint satisfaction

Abstract

Conjunctive-query containment is recognized as a fundamental problem in database query evaluation and optimization. At the same time, constraint satisfaction is recognized as a fundamental problem in artificial intelligence. Despite their very different formulation, it its shown that both are essentially the same problem. The several cases of tractable non-uniform constraint satisfaction problems that uniformize are investigated. Three non-uniform tractability results that uniformize and, thus, give rise to polynomial-time solvable cases of constraint satisfaction and conjunctive-query containment are presented.