J. J. Alferes, C. V. Dam'asio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, ILPS'94, pages 424--438. MIT Press, 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Trying to prove p in P 1 Prolog applies the rule p p over and over again. A similar reason stops P 2 from terminating in Prolog. The problems occur in general due to positive or negative loops through recursion. To deal with this problem we de ne T and TU trees, to prove verity and non falsity [ADP94a, ADP94b, ADP95, AP96]. De nition 8 Fuzzy T tree, TU tree Let P be a ground fuzzy extended logic program, let true be a new unary predicate symbol, and let P 0 be the program obtained from P by replacing rules of the form L with L true(1) and rules of the form L : V with L true(V ) A fuzzy T tree (resp. ....

J. J. Alferes, C. V. Damasio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, Proc. of the International Logic Programming Symposium '94, pages 424-438. MIT Press, November 1994.

....[Dun93, DDS93, HT93, Tur94, ALP94] To be able to actually answer queries to D we need to use a particular query answering algorithm. The standard Prolog interpreter (as implemented for instance in Quintus 3 Prolog) is certainly the most popular among the large family of such algorithms [CSW95, ADP94] and seems to be a natural choice for use in this paper. Consequently, we view D as a Prolog program and prove soundness and completeness of the Prolog inference mechanism w.r.t. the answer set semantics [GL91] of D . 4 In the last part of the paper, we discuss an implementation of the ....

.... More general and more ecient methods of computing the entailment of L 1 and its extensions should be found. One possibility is to investigate other inference mechanisms which are sound w.r.t. declarative logic programming semantics. For programs with unique answer sets, the SLX procedure from [ADP94, ADP95] is a promising candidate. It computes answers w.r.t. the well founded [VGRS91, PAA92] semantics of logic programs and hence is sound w.r.t. the answer set semantics. An interesting and challenging problem is to expand SLX by allowing disjunction and therefore reasoning by cases. Another ....

J. Alferes, C. Damasio, and L. Pereira. SLX { A top-down derivation procedure for programs with explicit negation. In Proc. of International Logic Programming Symposium 94, pages 424-438, 1994. 22 They do point out that these assumptions can be weakened using abduction. 40

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J. J. Alferes, C. V. Dam'asio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, ILPS'94, pages 424--438. MIT Press, 1994.

.... all extensions of a state of the art diagnoser, such as preferences and strategies [FNS94,NFS95] can be incorporated into the existing approach [DNPS95] The more recent second implementation of REVISE is based on a new top down evaluation of well founded semantics with explicit negation (WFSX) [ADP94a,ADP94b,ADP95], which lead to a dramatic speed increase. The REVISE system is embedded into an architecture for a diagnosis agent consisting of three layers: a knowledge base, an inference layer, and on top a component for communication and control (see Fig. 1) The core of the inference machine is the REVISE ....

J. J. Alferes, C. V. Damasio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, Proc. of the International Logic Programming Symposium'94, pages 424--438. MIT Press, November 1994.

.... M , LA, and GA, where M is either t or tu indicating that we want to prove verity (t) and non falsity (tu) and LA and GA are lists of local and global ancestors that allow to detect negative and positive loops which lead to inference of non falsity and failure, respectively (for details see[1, 2, 4]) Definition 3.1 Let P be an extended logic program and Body a sequence of literals L 1 ; L l ; not L l 1 ; not Lm , then P L iff P; t L P; M L iff P; M L P; LA;GA;M true P; LA;GA;M (L 1 ; L 2 ) iff P; LA;GA;M L 1 P; LA;GA;M L 2 P; LA;GA;M not L ....

J. J. Alferes, C. V. Dam'asio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, Proc. of the International Logic Programming Symposium'94, pages 424--438. MIT Press, November 1994.

.... LA, and GA, where M is either t or tu indicating that we want to prove verity (t) and non falsity (tu) respectively, LA and GA are lists of local and global ancestors that allow to detect negative and positive loops which lead to inference of non falsity and failure, respectively; for details see [1,2,4]. For consistent programs the above inference operator yields the same results as the argumentation process: Proposition 9. Relation of j= and Argumentation Let P be consistent. P; t j= L, iff L is a conclusion from a justified argument. P; t j= notL, iff L is a conclusion from an overruled ....

J. J. Alferes, C. V. Damasio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, Proc. of the International Logic Programming Symposium'94, pages 424--438. MIT Press, November 1994.

....as shown in section 4. At first reading the section below may be skipped. 2. 2 WFSX Semantics: a Top Down Proof Procedure WFSX, the well founded semantics, enjoys the properties of simplicity, cumulativity, rationality, relevance, and partial evaluation that other semantics do not fully enjoy [4,1,2]. Simplicity means that the semantics can be characterised by two iterative operators, without recourse to three valued logic. Cumulativity means that the addition of lemmas, i.e. true propositions, to the program does not change the semantics. Rationality refers to the ability to add ....

....created. In order to prove not p true, all TU trees for p have to fail. Thus, an infinite loop occurs and therefore the nodes in the TU tree are eventually classified as failed and the nodes in the T tree as successful, so that p is proved true. p not p p not p p Theorem 10. Correctness [1,2,4] Let P be a ground, possibly infinite, extended logic program, M its well founded model according to WFSX, and let L be an arbitrary fixed literal. If there is a successful T tree with root L then L 2 M (soundness) If L 2 M then there is a successful T tree with root L (completeness) As ....

J. J. Alferes, C. V. Damasio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, Proc. of the International Logic Programming Symposium'94, pages 424--438. MIT Press, November 1994.

.... [DNP94] Also all extensions of a state of the art diagnoser such as preferences and strategies [FNS94, NFS95] can be incorporated into the existing approach [DNPS95] The second implementation of REVISE is based on top down evaluation of well founded semantics with explicit negation (WFSX) [ADP94a, ADP94b], which led to a dramatic speed increase. In this system description we give an overview over the system s architecture and we evaluate and compare the implemented prototypes. Minimal Node Revision Tree WFSX Interpreter Preferences Conflicts REVISE Diagnosis Agent Knowledge Base Inference Engine ....

J. J. Alferes, C. V. Dam'asio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, Proc. of the International Logic Programming Symposium'94, pages 424--438. MIT Press, November 1994.

.... WFSX p , a less expressive semantics (if P 6= NP ) and that by adding abduction we obtain the same expressive power as an abductive framework built on top of a more expressive semantics (Stable Models) This is an advantage, because more efficient top down proof procedures are defined for WFSX [2]. Not using explicit negation in the abductive framework transformations needs some care. When we define our abductive frameworks, we will omit the condition if L is an abducible then :L is also abducible. For the sake of simplicity, we assume we make all these explicitly negated literals ....

J. J. Alferes, C. V. Dam'asio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, ILPS'94, pages 424--438. MIT Press, 1994.

....within a concurrent logic programming framework. In particular, our approaches includes the definition of an observation thought action cycle and the meta predicate demo. The main difference between the demo definitions is that we define top down evaluation of extended logic programs [ADP94a, ADP94b] and thus allow for implicit and explicit negation and constraints and that we use the demo predicate to abduce actions. Furthermore, Kow95] aims to reconcile reactive with rational agents and thus carefully treats bounded rationality of logical agents. We did not tackle this issue, but due to ....

J. J. Alferes, C. V. Dam'asio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, Proc. of the International Logic Programming Symposium'94, pages 424-- 438. MIT Press, November 1994.

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ADP94b J. J. Alferes, C. V. Dam asio, and L. M. Pereira. A top-down derivation procedure for programs with explicit negation. In M. Bruynooghe, editor, Proc. of the International Logic Programming Symposium'94, pages 424--438. MIT Press, November 1994.

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