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60
Tabled Evaluation with Delaying for General Logic Programs
, 1996
"... SLD resolution with negation as finite failure (SLDNF) reflects the procedural interpretation of predicate calculus as a programming language and forms the computational basis for Prolog systems. Despite its advantages for stackbased memory management, SLDNF is often not appropriate for query evalu ..."
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Cited by 260 (27 self)
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SLD resolution with negation as finite failure (SLDNF) reflects the procedural interpretation of predicate calculus as a programming language and forms the computational basis for Prolog systems. Despite its advantages for stackbased memory management, SLDNF is often not appropriate for query evaluation for three reasons: a) it may not terminate due to infinite positive recursion; b) it may not terminate due to infinite recursion through negation; c) it may repeatedly evaluate the same literal in a rule body, leading to unacceptable performance. We address three problems fir a goaloriented query evaluation of general logic programs by presenting tabled evaluation with delaying (SLG resolution).
Regular Path Queries with Constraints
 SYMPOSIUM ON PRINCIPLES OF DATABASE SYSTEMS
, 1997
"... The evaluation of path expression queries on semistructured data in a distributed asynchronous environment is considered. The focus is on the use of local information expressed in the form of path constraints in the optimization of path expression queries. In particular, decidability and complexity ..."
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Cited by 147 (6 self)
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The evaluation of path expression queries on semistructured data in a distributed asynchronous environment is considered. The focus is on the use of local information expressed in the form of path constraints in the optimization of path expression queries. In particular, decidability and complexity results on the implication problem for path constraints are established.
SSemantics Approach: Theory and Applications
, 1994
"... The paper is a general overview of an approach to the semantics of logic programs whose aim is finding notions of models which really capture the operational semantics, and are therefore useful for defining program equivalences and for semanticsbased program analysis. The approach leads to the intr ..."
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Cited by 115 (26 self)
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The paper is a general overview of an approach to the semantics of logic programs whose aim is finding notions of models which really capture the operational semantics, and are therefore useful for defining program equivalences and for semanticsbased program analysis. The approach leads to the introduction of extended interpretations which are more expressive than Herbrand interpretations. The semantics in terms of extended interpretations can be obtained as a result of both an operational (topdown) and a fixpoint (bottomup) construction. It can also be characterized from the modeltheoretic viewpoint, by defining a set of extended models which contains standard Herbrand models. We discuss the original construction modeling computed answer substitutions, its compositional version and various semantics modeling more concrete observables. We then show how the approach can be applied to several extensions of positive logic programs. We finally consider some applications, mainly in the area of semanticsbased program transformation and analysis.
Temporal Deductive Databases
, 1992
"... We survey a number of approaches to the problem of finite representation of infinite temporal extensions. Two of them, Datalog 1S and Templog, are syntactical extensions of Datalog; the third is based on repetition and arithmetic constraints. We provide precise characterizations of the expressivenes ..."
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Cited by 62 (9 self)
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We survey a number of approaches to the problem of finite representation of infinite temporal extensions. Two of them, Datalog 1S and Templog, are syntactical extensions of Datalog; the third is based on repetition and arithmetic constraints. We provide precise characterizations of the expressiveness and the computational complexity of these languages. We also describe query evaluation methods.
Caching and Lemmaizing in Model Elimination Theorem Provers
, 1992
"... Theorem provers based on model elimination have exhibited extremely high inference rates but have lacked a redundancy control mechanism such as subsumption. In this paper we report on work done to modify a model elimination theorem prover using two techniques, caching and lemmaizing, that have reduc ..."
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Cited by 49 (2 self)
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Theorem provers based on model elimination have exhibited extremely high inference rates but have lacked a redundancy control mechanism such as subsumption. In this paper we report on work done to modify a model elimination theorem prover using two techniques, caching and lemmaizing, that have reduced by more than an order of magnitude the time required to find proofs of several problems and that have enabled the prover to prove theorems previously unobtainable by topdown model elimination theorem provers.
Towards a Uniform Formal Framework for Parsing
 Current Issues in Parsing Technology
, 1991
"... Introduction Many of the formalisms used to define the syntax of natural (and programming) languages may be located in a continuum that ranges from propositional Horn logic to full first order Horn logic, possibly with nonHerbrand interpretations. This structural parenthood has been previously rem ..."
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Cited by 48 (3 self)
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Introduction Many of the formalisms used to define the syntax of natural (and programming) languages may be located in a continuum that ranges from propositional Horn logic to full first order Horn logic, possibly with nonHerbrand interpretations. This structural parenthood has been previously remarked: it lead to the development of Prolog [Col78, Coh88] and is analyzed in some detail in [PerW80] for ContextFree languages and Horn Clauses. A notable outcome is the parsing technique known as Earley deduction [PerW83]. These formalisms play (at least) three roles: descriptive: they give a finite and organized description of the syntactic structure of the language, analytic: they can be used to analyze sentences so as to retrieve a syntactic structure (i.e. a representation) from which the meaning can be extracted, generative: they can also be used as the specification of the concrete representation of sentences from a more
XSB: A System for Efficiently Computing WellFounded Semantics
 In Proceedings of the 4th International Conference on Logic Programming and NonMonotonic Reasoning (LPNMRâ€™97
, 1997
"... The wellfounded model provides a natural and robust semantics for logic programs with negative literals in rule bodies. We implemented the wellfounded semantics in the SLGWAM of XSB. Performance results indicate that the overhead of delay and simplification to Prolog  or tabled  evaluations ..."
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Cited by 44 (4 self)
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The wellfounded model provides a natural and robust semantics for logic programs with negative literals in rule bodies. We implemented the wellfounded semantics in the SLGWAM of XSB. Performance results indicate that the overhead of delay and simplification to Prolog  or tabled  evaluations is minimal. To compute the wellfounded semantics, the SLGWAM adds to an efficient tabling engine three operations  negative loop detection, delay and simplification  which serve to detect, to break and to resolve the cycles through negation that arise in evaluating normal programs XSB is a full Prolog system that closely approximates the ISO standard; additionally, it supports tight integration of tabled predicates with nontabled predicates. 1 Introduction XSB is a researchoriented Logic Programming system for Unix and Windows/DOSbased systems. In addition to providing all the functionality of Prolog, XSB contains several features not usually found in Logic Programming systems, i...
An Abstract Machine for SLG Resolution: Definite Programs
 In Proceedings of the Symposium on Logic Programming
, 1994
"... This paper addresses the correctness of the SLGWAM for definite programs, and describes its architecture for executing these programs. We argue its correctness through a restriction of SLGO, an operational semantics for SLG, which models the actions of the SLGWAM. We then offer a detailed descript ..."
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Cited by 35 (13 self)
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This paper addresses the correctness of the SLGWAM for definite programs, and describes its architecture for executing these programs. We argue its correctness through a restriction of SLGO, an operational semantics for SLG, which models the actions of the SLGWAM. We then offer a detailed description of the algorithms, data structures and instructions of the SLGWAM, and a performance analysis of engine overhead due to the extensions. 1 Introduction The lack of finiteness of SLD, even on datalog programs, is a wellknown problem. Despite much research, there is no general agreement on the best solution to this problem. Some papers advocate a setatatime solution, usually based on a variant of magic sets [1] (but see also [13]); others prefer a tupleatatime approach based on tabling, such as OLDT [11], or Extension Tables [5]; mixtures are also possible as in SLDAL [12].
Goal Independency and Call Patterns in the Analysis of Logic Programs
 IN PROCEEDINGS OF THE NINTH ACM SYMPOSIUM ON APPLIED COMPUTING
, 1994
"... We propose an abstract semantics for the goal independent analysis of properties of "procedure calls" in SLD derivations (call patterns). This can be used to derive information useful for logic program optimizations. ..."
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Cited by 29 (3 self)
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We propose an abstract semantics for the goal independent analysis of properties of "procedure calls" in SLD derivations (call patterns). This can be used to derive information useful for logic program optimizations.
An Algebraic Theory of Observables
, 1994
"... We give an algebraic formalization of SLDtrees and their abstractions (observables) . We can state and prove in the framework several useful theorems (ANDcompositionality, correctness and full abstraction of the denotation, equivalent topdown and bottomup constructions) about semantic properties ..."
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Cited by 28 (9 self)
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We give an algebraic formalization of SLDtrees and their abstractions (observables) . We can state and prove in the framework several useful theorems (ANDcompositionality, correctness and full abstraction of the denotation, equivalent topdown and bottomup constructions) about semantic properties of various observables. Observables are represented by Galois coinsertions and can be used to model abstract interpretation. The constructions and the theorems are inherited by all the observables which can be formalized in the framework. The power of the framework is shown by reconstructing some known examples (answer constraints, call patterns, correct call patterns and ground dependencies call patterns). 1 Introduction SLDtrees are structures used to describe the operational semantics of logic programs. From an SLDtree we can derive several operational properties which are useful for reasoning about programs. Examples are SLD  derivations, resultants, call patterns, partial answers,...