TY - JOUR
T1 - Bounds on the propagation of selection into logic programs
AU - Beeri, Catriel
AU - Kanellakis, Paris
AU - Bancilhon, Francois
AU - Ramakrishnan, Raghu
PY - 1990/10
Y1 - 1990/10
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0025500078&partnerID=8YFLogxK
U2 - 10.1016/0022-0000(90)90035-J
DO - 10.1016/0022-0000(90)90035-J
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AN - SCOPUS:0025500078
SN - 0022-0000
VL - 41
SP - 157
EP - 180
JO - Journal of Computer and System Sciences
JF - Journal of Computer and System Sciences
IS - 2
ER -