Generalized Query Answering in Disjunctive Databases
Using Minimal Model Generation

by 

Adnan Yahya

Institut fuer Informatik, Ludwig-Maximilians-Universitaet, Munich, Germany.
and
Electrical Engineering Department, Birzeit University, Birzeit, Palestine.

Email: yahya@informatik.uni-muenchen.de


Abstract

Minimal models underly one of the major semantics for disjunctive theories 
and a substantial research effort was directed at minimal model reasoning. 
In this paper we investigate the process of generalized query answering under 
the minimal model semantics for the class of Disjunctive Deductive Databases. 
We cover several classes of queries that are of practical importance for 
database maintenance. Answers that are true in {\em all} and those that are 
true in {\em some} minimal models of the theory are considered and their 
monotonicity properties are discussed.
Our approach is based on having the generalized query induce an order on the 
models returned by  a sound and complete minimal  model generating procedure. 
This makes it possible to introduce  refinements to the query answering 
process such as allowing the specification of conditions under which a query 
becomes derivable from the database and checking for answer minimality.