Processing negation and disjunction in logic programs through integrity constraints

摘要

Integrity constraints were initially defined to verify the correctness of the data that is stored in a database. They were used to restrict the modifications that can be applied to a database. However, there are many other applications in which integrity constraints can play an important role. For example, the semantic query optimization method developed by Chakravarthy, Grant, and Minker for definite deductive databases uses integrity constraints during query processing to prevent the exploration of search space that is bound to fail. In this paper, we generalize the semantic query optimization method to apply to negated atoms. The generalized method is referred to assemantic compilation. This exploration has led to two significant results. First, semantic compilation provides an alternative search space for negative query literals. The alternative search space can find answers in cases for which negation-as-finite-failure and constructive negation cannot. Second, we show how semantic compilation can be used to transform a disjunctive database with or without functions and denial constraints without negation into a new disjunctive database that complies with the integrity constraints.