TY - JOUR
T1 - More on tractable disjunctive Datalog
AU - Ben-Eliyahu-Zohary, Rachel
AU - Palopoli, Luigi
AU - Zemlyanker, Victoria
N1 - Funding Information:
The work of the first author was supported in part by grants NSF IRI-88-21444 and AFOSR 90-0136. The second author is supported in part by ECC under the ECUS project ``DEUS EX MACHINA: non-determinism for deductive databases'' and by a MURST grant (40% share) under the project ``Sistemi formali e strumenti per basi di dati evolute''. Thanks to Giovambattista Ianni, Nicola Leone, and Francesco Scarcello for useful comments and discussions.
PY - 2000/1/1
Y1 - 2000/1/1
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0034325673&partnerID=8YFLogxK
U2 - 10.1016/S0743-1066(99)00066-7
DO - 10.1016/S0743-1066(99)00066-7
M3 - Article
AN - SCOPUS:0034325673
SN - 0743-1066
VL - 46
SP - 61
EP - 101
JO - Journal of Logic Programming
JF - Journal of Logic Programming
IS - 1
ER -