A Top-Down Query Answering Procedure for Normal Logic Programs Under the Any-World Assumption

Abstract

The Any-World Assumption (AWA) has been introduced for normal logic programs as a generalization of the well-known notions of Closed World Assumption (CWA) and the Open World Assumption (OWA). The AWA allows anyassignment (i.e., interpretation), over a truth space(bilattice), to be a default assumption and, thus, the CWA and OWA are just special cases. To answer queries, we provide a novel and simple top-down procedure.