P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....can be accomplished by a suitable generalization of Clark s completion but it only works for a restricted class of knowledge bases, namely those whose clauses do not have any objective premises. Such residual databases were previously introduced and investigated in the class of logic programs [Bry89, Bry90, DK89a, DK89b, BD97c, BD95]. Here we give a slightly more general definition. 10 Definition 3.1 (Residual Knowledge Bases [BD95] By a residual knowledge base we mean an arbitrary non monotonic knowledge base whose clauses do not contain any objective (positive) premises, i.e. a (possibly infinite) set of arbitrary ....

P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

....can be accomplished by a suitable generalization of Clark s completion but it only works for a restricted class of knowledge bases, namely those whose clauses do not have any objective premises. Such residual databases were previously introduced and investigated in the class of logic programs [16, 17, 26, 27, 10, 7]. Here we give a slightly more general definition. 14 Definition 3.1 (Residual Knowledge Bases [7] By a residual knowledge base we mean an arbitrary non monotonic knowledge base whose clauses do not contain any objective (positive) premises, i.e. a (possibly infinite) set of arbitrary clauses ....

P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

.... that compute the well founded model of a normal program are: The alternating fixpoint approach, introduced by Van Gelder [23, 24] and further developed by Kemp, Stuckey and Srivastava [19] The residual program approach, suggested by Bry [8, 9] and independently by Dung Kanchanasut [15, 16], and extended by Brass and Dix [4, 5] The alternating fixpoint procedure is known to have efficiency problems, since in every iteration many facts have to be recomputed. The residual program approach avoids recomputations of this kind. But it is possible that the residual program can grow to ....

P. M. Dung and K. Kanchansut. A natural semantics of logic programs with negation. In Proc. of the Ninth Conf. on Foundations of Software Technology and Theoretical Computer Science, pages 70--80, 1989.

....essentially the same as the securable set in [36] Unfounded sets are defined in Section 3. Since the preliminary version of this paper was presented at a conference [43] several alternative formulations of negation that appear to be equivalent to the well founded semantics have been developed [3, 8, 32, 42]. We believe that this indicates a robustness of the semantics, and provides evidence that it coincides well with common sense and intuition. 2 General Logic Programs and Partial Interpretations In this section we introduce our notation and basic definitions, and describe the class of general ....

Ph. M. Dung and K. Kanchanasut. A natural semantics for logic programs with negation. Technical report, Asian Institute of Technology, Bankok 10501, Thailand, 1989. (manuscript).

....i.e. ground rules without positive body literals . Conditional facts result from delaying the negative body literals during a bottom up evaluation of an allowed logic program (the delayed literals are attached as conditions to the derived facts) Conditional facts have already been studied in [Bry89, Bry90, DK89b, DK89a, HY91] (for non disjunctive programs) We especially generalize the TP operator and the reductions introduced by Bry to the disjunctive case. However, our main result is the relation of this bottom up computation to our elementary program transformations. 2. A consequence of this is that the residual ....

....program. In contrast to the last section, we no longer work on instantiated programs. However, we use the allowedness condition to bind the variables and avoid floundering. Our approach is based on the notion of conditional facts , as developed by Bry in [Bry89, Bry90] and Dung Kanchansut in [DK89b, DK89a] (both for the non disjunctive case) The idea is to delay the evaluation of negative body literals, and to attach them as conditions to the derived (disjunctive) facts. Definition 3.1. Conditional Fact) A conditional fact is a rule without positive body literals, i.e. it is of the form A 1 ....

P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

....of the alternating fixpoint procedure: while true facts can be derived incrementally, some information about possible answers needs to be recomputed in every iteration step. Thus, even some very simple programs are evaluated with suboptimal efficiency. Bry [Bry89] and Dung and Kanchanasut [DK89] introduced independently the notion of conditional facts and the conditional fixpoint procedure. Brass and Dix [BD95a, BD95b] extended this work to a more general partial evaluation framework. They showed that this method can be used to compute the well founded semantics as well as further ....

....To avoid this recomputation, for each possible answer the information on which negative subgoals it depends should be recorded. To this end, we annotate each possible fact, i.e. each member of an U i , by a set of negative subgoals that are still to be proven. Definition 4. 1 [Conditional Facts [Bry89, DK89]] A conditional fact is a ground clause of the form A :B 1 ; Bn . It can also be denoted by A : DeltaC where C is the set of atoms C = fB 1 ; B n g. A set of conditional facts is called quasi interpretation. For a quasi interpretation I we define the following sets: facts(I) fA ....

P. M. Dung and K. Kanchanasut. A natural semantics for logic programs with negation. In Proc. Conf. Found. of Software Technology and Theor. Computer Science, pp. 78--88, 1989.

....can be accomplished by a suitable generalization of Clark s completion but it only works for a restricted class of knowledge bases, namely those whose clauses do not have any objective premises. Such residual databases were previously introduced and investigated in the class of logic programs [16, 17, 26, 27, 10, 7]. Here we give a slightly more general definition. Definition 3.1 (Residual Knowledge Bases [7] By a residual knowledge base we mean an arbitrary non monotonic knowledge base whose clauses do not contain any objective (positive) premises, i.e. a (possibly infinite) set of arbitrary clauses of ....

P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

....can be accomplished by a suitable generalization of Clark s completion but it only works for a restricted class of knowledge bases, namely those whose clauses do not have any objective premises. Such residual databases were previously introduced and investigated in the class of logic programs [Bry89, Bry90, DK89a, DK89b, BD97c, BD95]. Here we give a slightly more general definition. Definition 3.1 (Residual Knowledge Bases [BD95] By a residual knowledge base we mean an arbitrary non monotonic knowledge base whose clauses do not contain any objective (positive) premises, i.e. a (possibly infinite) set of arbitrary clauses ....

P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

.... compute the well founded model of a normal program are: The alternating fixpoint approach, introduced by Van Gelder [27, 28] and further developed by Kemp, Stuckey and Srivastava [20] The computation of the residual program, suggested by Bry [9, 10] and independently by Dung Kanchanasut [16, 17], and extended by Brass and Dix [6, 7] The alternating fixpoint procedure is known to have efficiency problems, since in every iteration many facts have to be recomputed. The residual program approach avoids recomputations of this kind. But it is still possible that the residual program can grow ....

....and P 2 7 R P 3 . Thus, every program P has a unique normalform, which is called the residual program res(P ) of P . 2 Obviously, rules in the residual program cannot contain positive body literals, since then unfolding would be applicable. So the residual program is a set of conditional facts [9, 10, 16, 17]: Definition14 Conditional Fact. A conditional fact is a ground rule with only negative body literals, i.e. a rule of the form A notB 1 Delta Delta Delta notBn . 2 As shown in [6] the well founded semantics is the weakest semantics which allows the above transformations. We can directly ....

P. M. Dung and K. Kanchansut. A natural semantics of logic programs with negation. In Proc. of the Ninth Conf. on Foundations of Software Technology and Theoretical Computer Science, pages 70--80, 1989.

....task can be accomplished by a suitable generalization of Clark s completion but it only works for a restricted class of belief theories, namely those whose clauses do not have any objective premises. Such residual theories were previously introduced and investigated in the class of logic programs [6, 7, 9, 10, 4, 1]. Here we give a slightly more general definition. Definition 3.1 (Residual Belief Theories [1] By a residual belief theory we mean an arbitrary belief theory whose clauses do not contain any objective (positive) premises, i.e. a (possibly infinite) set of arbitrary clauses BG 1 : BG k ....

P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

....to provide proof for every semantics. Instead we wish to exploit the relationship among all these semantics. In this paper, we first observe that to show the correctness of unfold fold transformation system wrt various semantics of negation, it is enough if the correctness wrt the semantic kernel [16,17] of a normal program is shown. Later, we prove that the unfold fold framework preserves the semantic kernel of a normal program and obtain previous and new results of the field as corollaries of our main theorem. Apart from the correctness results for normal programs, we also show that it is easy ....

....other semantics of normal logic programs. To capture the intended meaning of a normal logic program in 2 [27] defines a computed answer substitution of a goal G wrt program P as a pair (G,q) s.t. there exists a proof tree of G wrt P with answer substitution q. Page: 5 19 a more natural way, in [16,17] Dung et al. defined the semantic kernel 3 of a normal program. The idea starts with the concept of a quasi interpretation, which is formally defined below. Definition 3.1 (Quasi interpretation) A quasi interpretation I is a set of ground program clauses of the form, A not B 1 , not B n ....

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Dung,P.M. and Kanchanasut,K., A natural semantics for logic programs with negation, in: C.E. Veni Madhavan (Ed.), Foundations of software technology and theoretical computer science, LNCS 405, Springer-Verlag, 1989, pp. 78-88.

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P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

No context found.

P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

No context found.

P. M. Dung and K. Kanchansut. A natural semantics for logic programs with negation. In E.L. Lusk and R.A. Overbeek, editors, Proceedings of the 9th Conference on Foundations of Software Technology and Theoretical Computer Science, Berlin, 1989. Springer.

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