An analysis of loop checking mechanisms for logic programs

Bol, Roland; Apt, Krzysztof R.; Klop, Jan Willem

doi:10.1016/0304-3975(91)90004-l

Cited by 63 publications

(64 citation statements)

References 12 publications

(21 reference statements)

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“…On the other hand, it is obvious that EV R L loop check cannot prune the infinite RSLD derivation developed in the same example, because the length of resolvents increases at each derivation step. Actually, it is immediate to verify that the infinite derivation in Example 2.2 cannot even be pruned by using more complex and powerful checks (like SIR M ) which are based on subsumption relationships between resultants (Bol, Apt and Klop, 1991). Now we prove that EV R L loop check completeness is preserved for function free programs, in the case that EV R L is complete with respect to all selection rules.…”

Section: Ev R L Loop Check Completenessmentioning

confidence: 87%

“…It is worth noting that EV G L is a weakly sound loop check, in sense that it preserves at least a successful, but it does not ensure the preservation of the computed answer substitutions (Bol, Apt and Klop, 1991).…”

Section: Ev R L Loop Check Completenessmentioning

confidence: 99%

“…The usual objective is to reduce the search space without loss of results of the refutation process, possibly obtaining a finite search space. Among the proposed methods, the loop check mechanisms (Apt, Bol and Klop, 1989), (Bol, Apt and Klop, 1991), (Smith, Genesereth and Ginsberg , 1986), (Van Gelder, 1987), and the tabulation technique (Bol & Degersted, 1998), (Dietrich, 1987), (Ramakrishnan et al, 1999), (Tamaki & Sato, 1986), (Vieille, 1989), aim to eliminate redundant computations and to enforce the termination of a query over a logic program.…”

Section: Introductionmentioning

confidence: 99%

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On redundancy elimination tolerant scheduling rules

Ferrucci¹,

Sessa²,

Pacini

2001

Theory and Practice of Logic Programming

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In (Ferrucci, Pacini and Sessa, 1995) an extended form of resolution, called Reduced SLD resolution (RSLD), is introduced. In essence, an RSLD derivation is an SLD derivation such that redundancy elimination from resolvents is performed after each rewriting step. It is intuitive that redundancy elimination may have positive effects on derivation process. However, undesiderable effects are also possible. In particular, as shown in this paper, program termination as well as completeness of loop checking mechanisms via a given selection rule may be lost. The study of such effects has led us to an analysis of selection rule basic concepts, so that we have found convenient to move the attention from rules of atom selection to rules of atom scheduling. A priority mechanism for atom scheduling is built, where a priority is assigned to each atom in a resolvent, and primary importance is given to the event of arrival of new atoms from the body of the applied clause at rewriting time. This new computational model proves able to address the study of redundancy elimination effects, giving at the same time interesting insights into general properties of selection rules. As a matter of fact, a class of scheduling rules, namely the specialisation independent ones, is defined in the paper by using not trivial semantic arguments. As a quite surprising result, specialisation independent scheduling rules turn out to coincide with a class of rules which have an immediate structural characterisation (named stack-queue rules). Then we prove that such scheduling rules are tolerant to redundancy elimination, in the sense that neither program termination nor completeness of equality loop check is lost passing from SLD to RSLD.

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Section: Ev R L Loop Check Completenessmentioning

confidence: 87%

Section: Ev R L Loop Check Completenessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On redundancy elimination tolerant scheduling rules

Ferrucci¹,

Sessa²,

Pacini

2001

Theory and Practice of Logic Programming

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“…In this area, [5] sets up some solid foundations. A loop check is a device to prune derivations when it seems appropriate.…”

Section: Related Workmentioning

confidence: 99%

Nontermination inference of logic programs

Payet

Mesnard

2006

ACM Trans. Program. Lang. Syst.

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We present a static analysis technique for non-termination inference of logic programs. Our framework relies on an extension of the subsumption test, where some specific argument positions can be instantiated while others are generalized. We give syntactic criteria to statically identify such argument positions from the text of a program. Atomic left looping queries are generated bottom-up from selected subsets of the binary unfoldings of the program of interest. We propose a set of correct algorithms for automating the approach. Then, non-termination inference is tailored to attempt proofs of optimality of left termination conditions computed by a termination inference tool. An experimental evaluation is reported. When termination and non-termination analysis produce complementary results for a logic procedure, then with respect to the leftmost selection rule and the language used to describe sets of atomic queries, each analysis is optimal and together, they induce a characterization of the operational behavior of the logic procedure.

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“…[12]). While a run-time analysis is potentially able to cut more unsuccessful branches, the evaluation of a pruning condition at run-time, such as for loop checks, involves a considerably higher computational overhead than statically checking the boundedness proof obligations.…”

Section: Bounded Nondeterminismmentioning

confidence: 99%

Characterisations of Termination in Logic Programming

Pedreschi

Ruggieri

Smaus

2004

Program Development in Computational Logic

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Abstract. The procedural interpretation of logic programs and queries is parametric to the selection rule, i.e. the rule that determines which atom is selected in each resolution step. Termination of logic programs and queries depends critically on the selection rule. In this survey, we present a unified view and comparison of seven notions of universal termination considered in the literature, and the corresponding classes of programs. For each class, we focus on a sufficient, and in most cases even necessary, declarative characterisation for determining that a program is in that class. By unifying different formalisms and making appropriate assumptions, we are able to establish a formal hierarchy between the different classes and their respective declarative characterisations.

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An analysis of loop checking mechanisms for logic programs

Cited by 63 publications

References 12 publications

On redundancy elimination tolerant scheduling rules

On redundancy elimination tolerant scheduling rules

Nontermination inference of logic programs

Characterisations of Termination in Logic Programming

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