Recursively indefinite databases (extended abstract)

Authors:
R. van der Meyden
Affiliations:
-
Venue:
ICDT '90 Proceedings of the third international conference on database theory on Database theory
Year:
1990

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Abstract

We define recursively indefinite databases, a new type of logical database in which indefinite information arises from partial knowledge of the fixpoint of a datalog program. Although, in general, query answering is undecidable, there exists a broad class of queries for which it is decidable, a result we establish by making connections with the theory of hypergraph edge replacement graph grammars. We analyze the complexity of query answering for this class of queries under various constraints and demonstrate a class of databases which generalizes disjunctive databases, but without increasing data complexity.