Bounds on the propagation of selection into logic programs

Catriel Beeri*, Paris Kanellakis, Francois Bancilhon, Raghu Ramakrishnan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

We consider the problem of propagating selections into logic programs (i.e., recursive Horn clause programs). In particular, we study the class of chain programs and formalize selection propagation on such a logic program as: the task of finding an equivalent program containing only monadic derived predicates. Selection propagation is always possible for database programs (i.e., first-order formula programs) and is often a desirable optimization. We show that the situation is qualitatively different for logic programs. We associate a context free language L(H) with every chain program H. We show that, given H, propagating a selection involving some constant is possible iff L(H) is regular and therefore undecidable. We also show that propagating a selection of the form p(X, X) is possible iff L(H) is finite and therefore decidable. We demonstrate the connection of these two cases, respectively, with the weak monadic second-order theory of one successor and with monadic generalized spectra. We further clarify the analogy between chain programs and context-free languages from the point of view of program equivalence, first-order expressibility over finite structures, and selection propagation heuristics.

Original languageEnglish
Pages (from-to)157-180
Number of pages24
JournalJournal of Computer and System Sciences
Volume41
Issue number2
DOIs
StatePublished - Oct 1990

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