A Strong Containment Problem for Queries in Conjunctive Form with Negation

Abstract

In this paper we define a new notion of containment for two queries, called strong containment. The strong containment implies the classical containment. A necessary and sufficient condition for the strong containment relation between two queries is given. The time complexity of the decision problem for two queries to be in strong containment relation is a linear function of the containment mappings number corresponding to the queries