C. A. Johnson

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The view update problem is concerned with indirectly modifying those tuples that satisfy a view (or derived table) by an appropriate update against the corresponding base tables. The notion of a deduction tree is defined and the relationship between such trees and the view update problem for indefinite deductive databases is considered. It is shown that a(More)
The relationship between cyclic covers and perfect models of indefinite stratified deductive databases is discussed with respect to query answering, view updates and partial evaluation. The notion of a conjunctive answer to a database query is introduced, and such answers are shown to have a number of advantages over (the more commonly studied) "(More)
A method is presented for computing minimal answers of the form A in disjunctive deductive databases under the disjunctive stable model semantics. Such answers are constructed by repeatedly extending partial answers. Our method is complete (in that every minimal answer can be computed) and does not admit redundancy (in the sense that every partial answer(More)