Negation as failure: A comparison of Clark’s completed data base and Reiter’s closed world assumption. (English) Zbl 0575.68094

Shepherdson, John C.

J. Logic Program. 1, 51-79 (1984).

It is known (Clark 78) that the ”negation as failure” rule can be regarded as making deductions from the ”iff-completed” data base. This paper proves the same with respect to the ”closed world assumption” (Reiter 78). Their compatibility and equivalence are shown in case of definite Horn databases.

Reviewer: E.Knuth

MSC:

68P20

Information storage and retrieval of data

Keywords:

query completeness; definite Horn databases