Generalized Query Answering in Disjunctive Deductive Databases: Procedural and Non-Monotonic Aspects

Generalized queries are deened as sets of clauses in implication form. They cover several tasks of practical importance for database maintenance such as answering positive queries, computing database completions and integrity constraints checking. We address the issue of answering generalized queries under the minimal model semantics for the class of Disjunctive Deductive Databases (DDDBs). Our approach is based on having the query induce an order on the models returned by a sound and complete minimal model generating procedure. We consider answers that are true in all and those that are true in some minimal models of the theory and investigate the monotonicity properties of the diierent classes of queries and answers.