Efficient instance retrieval of subgoals for subsumptive tabled evaluation of logic programs

• Type: Article in International Scientific Journal
• Date: 2011

Authors

Flavio Cruz (Author) Other; Ricardo Rocha (Author) FCUP

Journal

Title: Theory and Practice of Logic Programming

Vol. 11

Pages: 697-712

ISSN: 1471-0684

Publisher: Cambridge University Press

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 1 Citation

Scientific classification

FOS: Natural sciences > Computer and information sciences

Other information

Authenticus ID: P-002-Q2P

DOI: 10.1017/s1471068411000251

Abstract (EN): Tabled evaluation is an implementation technique that solves some problems of traditional Prolog systems in dealing with recursion and redundant computations. Most tabling engines determine if a tabled subgoal will produce or consume answers by using variant checks. A more refined method, named call subsumption, considers that a subgoal A will consume from a subgoal B if A is subsumed by (an instance of) B, thus allowing greater answer reuse. We recently developed an extension, called Retroactive Call Subsumption, that improves upon call subsumption by supporting bidirectional sharing of answers between subsumed/subsuming subgoals. In this paper, we present both an algorithm and an extension to the table space data structures to efficiently implement instance retrieval of subgoals for subsumptive tabled evaluation of logic programs. Experiments results using the YapTab tabling system show that our implementation performs quite well on some complex benchmarks and is robust enough to handle a large number of subgoals without performance degradation.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16