Well-founded semantics for integrity constraints

In this paper we present a framework for consistency checking of a database with respect to its integrity constraints, overcoming the restriction of considering stratified databases only. To reach this goal we have considered the well-founded and stable models semantics and then decided to use the well-founded one. The basic idea is that of finding the widest class of transactions for which it can be stated that the updated database D' satisfies the integrity constraints IC, without having to compute its entire well-founded model, WF(D'). To this purpose the concept of conservative transactions has been introduced and furthermore a method to compute a (suitable approximation of the) minimal subset of WF(D') that permits to decide the satisfiability of contraints is presented.