More on tractable disjunctive Datalog

Rachel Ben-Eliyahu-Zohary, Luigi Palopoli, Victoria Zemlyanker

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Sometimes it is more natural to express knowledge in disjunctive Datalog rather than in ordinary Datalog. Several highly complex variants of disjunctive Datalog have been proposed in the past and their expressive power has been studied. In this paper we investigate tractable fragments of disjunctive Datalog. Algorithms are presented to answer queries defined using these fragments and their complexity analyzed. Furthermore, the expressive power of these tractable subsets is studied. The most expressive of the languages considered here is shown to express, in some sense explained in the paper, all polynomial time queries. This is the first identified fragment of disjunctive Datalog with this property.

Original languageEnglish
Pages (from-to)61-101
Number of pages41
JournalJournal of Logic Programming
Issue number1
StatePublished - 1 Jan 2000


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