M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Supported by GOA 93 97 03 1 Introduction Recently a number of high level languages have been proposed for modeling actions and change, as a tool for studying the principles underlying time and causality in particular simplified settings. The first of these languages to emerge, the A language of [10], models inertia and direct effects of actions in a branching time topology, with possible uncertainty on the initial state of the world. Extensions of A tackle gradually more complex issues: for example AR 0 ( 16] deals with indirect effects of actions (ramifications) and simple forms of ....

M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

.... role of abductive logic programming for representing uncertainty in a logic programming formalism and the role of abductive procedures for abductive and deductive reasoning and satisfiability checking on incomplete knowledge has been shown in the context of a translation from a temporal language A [27] to abductive logic programming. In the past, a number of abductive extensions of SLDNF resolution have been proposed for abductive logic programs with negation [21] 52] 46, 45, 44] 31] 8] 51] 29] 13] 54] Anticipating the discussion of these procedures in section 11, we can say ....

....the fact that reasoning by 2 cases on abducible predicates is possible. An important illustration of this thesis is found in the recent experiments on the transformation of the language A to extensions. In [17] we compare the transformation of A to Extended Logic Programming (ELP) presented in [27] with a transformation to abductive logic programming. The latter transformation is in all respects superior to the first one. In [17] we show that the reason for the incompleteness of the transformation of [27] is due to the fact that in ELP the law of excluded middle does not hold. One could ....

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M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

....perspective, this work can be viewed as a successfulexperiment in the declarative representation of and automated reasoning on incomplete knowledge using abductive logic programming. 1 Introduction An outstanding problem in logic programming is the representation of incomplete knowledge. In [17], Gelfond and Lifschitz propose an interesting methodology to evaluate the expressivity of a formalism for representing incomplete knowledge. They present a simple temporal language A for representing incomplete temporal knowledge and apply it successfully to a number of well known benchmark ....

....show the expressivity of this formalism for representing temporal knowledge and, more in general, incomplete knowledge. In the past, another approach has been explored for temporal reasoning, based on event calculus [13] 31] 25] 10] 10] proposes solutions for the same benchmarks as in [17]. This approach makes use of the formalism of abductive logic programming. One may interpret an abductive program as an open logic program in the sense that it contains only definitions for the non abducible predicates. The completion semantics for abductive logic programs of [3] reflects this ....

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M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

....logic programming. 1 Introduction The key issue in this paper is the representation of incomplete knowledge in a logic programming formalism. In pure Prolog, incomplete knowledge cannot be represented: due to negation as failure, an atom which cannot be proved is assumed to be false. Recently, [13] used extended programs to represent incomplete knowledge in the context of temporal domains. They introduced a new temporal language A which allows to represent a number of well known benchmark problems involving incomplete temporal knowledge and they proposed a sound transformation to extended ....

.... a sound transformation to extended programs, programs with both negation as failure and classical or explicit negation [12] In the past, another approach has been explored for temporal reasoning, based on event calculus [10] 21] 17] 8] 8] proposes solutions for the same benchmarks as in [13]. This approach makes use of the formalism of abductive logic programming. One may interpret an abductive program as an incomplete logic program in the sense that it contains only definitions for the non abducible predicates. The completion semantics for abductive logic programs of [3] reflects ....

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M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

....declarative language This work was partially supported by National Science Foundation under grant IRI 9101078. 1 The most notorious among such instances is the Yale shooting problem [Hanks and McDermott, 1987] for which a large number of solutions have been proposed. A, introduced in [ Gelfond and Lifschitz, 1992 ] In that paper, the authors also define a translation from A into the language of extended logic programs and prove its soundness. Our work is similar in that we provide simple translations from A into three different methodologies which have been proposed in the literature, but we prove both ....

....4 presents a translation based on Reiter s approach. In Section 5, we provide a translation which uses the circumscriptive approach. Section 6 contains concluding remarks. The proofs of all the theorems are omitted. 2 The Language A In this section, we describe the languge A introduced in [ Gelfond and Lifschitz, 1992 ] The reader who is interested in more examples and motivation is referred to that paper. Consider two disjoint nonempty sets of symbols, called fluent names and action names. A fluent expression is a fluent name possibly preceded by : A v proposition specifies the value of a fluent after ....

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Michael Gelfond and Vladimir Lifschitz. Describing action and change by logic programs. In Proc. Joint Int'l Conf. and Symp. on Logic Programming, 1992.

....assumptions; and (4) providing a semantic correspondence between the models selected by the entailment criterion and the models obtained from the underlying semantics. We also compare our methodology to Kartha s evaluation [6] of Reiter s general solution with respect to action logic semantics [4]. 1 Introduction This paper presents an application of Sandewall s methodology [16] for assessing nonmonotonic entailment criteria for reasoning about actions and change. We establish the correctness of Reiter s general solution to the frame problem based on the situation calculus [14] for a ....

....presented in Section 2. Sandewall s methodology is briefly presented in Section 3. In Section 4 we assess Reiter s solution according to Sandewall s methodology. In Section 5, we compare our methodology to Kartha s evaluation [6] of Reiter s general solution with respect to action logic semantics [4]. Finally, we present the conclusions and future work. 2 Reiter s General Solution Reiter [14] proposes a formalism to reason about action in first order logic. Building on work by Haas [5] Pednault [9] and Schubert [17] he syntactically transforms a preliminary axiomatization into a ....

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Gelfond, M. and Lifschitz, V.: Describing action and change by logic programs. Joint International Conference and Symposium on Logic Programming (1992)

....knowledge on action occurrences, action ordering and the initial state of the world. 1 Introduction Recently a number of high level languages have been proposed for modeling actions and change, as a tool for studying the principles underlying time and causality. The original A language ([GL92]) models inertia and direct effects of actions in a branching time topology, with possible uncertainty on the initial state of the world. Extensions of A tackle gradually more complex issues. The E language ( KM97] uses a narrativebased ontology modeled after the Event Calculus ( KS96] It ....

M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

.... that the formalism of abductive logic programs with first order logic constraints provides the same declarative expressivity for representing incomplete information as full first order logic (FOL) This was shown in [5] where it was exploited to provide an implementation of the A language of [10] in the Situation Calculus formulated as an abductive logic program. In this paper we demonstrate how a temporal database with incomplete information can be formalized in the Abductive Event Calculus and how a suitable abductive procedure like SLDNFA ( 6] which satisfies sufficiently strong ....

M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

....logic programming. 1 Introduction The key issue in this paper is the representation of incomplete knowledge in a logic programming formalism. In pure Prolog, incomplete knowledge cannot be represented: due to negation as failure, an atom which cannot be proved is assumed to be false. Recently, [17] used extended programs to represent incomplete knowledge in the context of temporal domains. They introduced a new temporal language A which allows to represent a number of well known benchmark problems involving incomplete temporal knowledge and they proposed a sound transformation to extended ....

.... a sound transformation to extended programs, programs with both negation as failure and classical or explicit negation [16] In the past, another approach has been explored for temporal reasoning, based on event calculus [13] 30] 25] 10] 10] proposes solutions for the same benchmarks as in [17]. This approach makes use of the formalism of abductive logic programming. One may interpret an abductive program as an open logic program in the sense that it contains only definitions for the non abducible predicates. The completion semantics for abductive logic programs of [3] reflects this ....

[Article contains additional citation context not shown here]

M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

....and (4) providing a semantic correspondence between the models selected by the entailment criterion and the models determined by the underlying semantics. We also compare our methodology to Kartha s evaluation [7] of Reiter s general solution with respect to the action logic semantics [4]. 1 Introduction We establish the correctness of Reiter s general solution to the frame problem [16] based on the situation calculus [9] for a broad and well characterized class of problems according to Sandewall s methodology [20] Reiter s solution consists of a compilation of a preliminary ....

....the situation calculus. Sandewall s methodology is briefly presented in Section 3. In Section 4 we assess Reiter s solution according to Sandewall s methodology. In Section 5, we compare our methodology to Kartha s evaluation [7] of Reiter s general solution with respect to action logic semantics [4]. Finally, we present our conclusions and sketch directions for future work. 2 Reiter s General Solution Reiter [16] proposes a formalism to reason about action in the situation calculus [9] Building on work by Haas [6] Pednault [10] and Schubert [21] he syntactically transforms a preliminary ....

[Article contains additional citation context not shown here]

M. Gelfond and V. Lifschitz. Describing action and change by logic programs. In Joint International Conference and Symposium on Logic Programming, 1992.

....on Situation Calculus. This makes certain forms of reasoning in particular counterfactual reasoning about action occurrences in the restricted version impossible that are possible in the original Situation Calculus. As a result, where a translation of descriptions in the language A ([11]) into Situation Calculus has been proved sound and complete in [7] such a translation into the restricted form of Situation Calculus of [14] is no longer possible. This problem is related to the fact that a translation of A descriptions into Event Calculus is also impossible. We therefore ....

....in [14] slightly modified versions of Situation Calculus and Event Calculus were shown to be equivalent. The main motivation for our research on this topic then was an unexpected problem arising during an attempt to provide a transformation from temporal domain descriptions in the A language ([11]) to (Open) Event Calculus theories. Where a transformation of A to (Open) Situation Calculus was established and proved sound and complete in [7] our proposed transformation to Event Calculus was incorrect. A detailed analysis pointed out that the problem could not be fixed by modifying the ....

M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

....three differences for knowledge representation and problem solving below. 5.1. 1 Branching Time The importance of the first difference, the use of branching versus linear time, came to our attention during an attempt to provide a transformation from temporal domain descriptions in the A language ( [ 9 ] ) to Abductive Event Calculus theories. Where a transformation of A to Abductive Situation Calculus was established and proven sound and complete in [ 5 ] our proposed transformation to Event Calculus was incorrect. A detailed analysis pointed out that the problem could not be fixed by ....

M. Gelfond and V. Lifschitz. Describing Action and Change by Logic Programs. In Proc. of the 9th Int. Joint Conf. and Symp. on Logic Programming, 1992.

....criterion and the models obtained from the underlying semantics. In particular, we assess the applicability of Reiter s solution to formalize database updates [16, 15] We also compare our methodology to Kartha s evaluation [6] of Reiter s general solution with respect to action logic semantics [4]. 1 Introduction This paper presents an application of Sandewall s methodology [17] for assessing nonmonotonic entailment criteria for reasoning about actions and change. We establish the correctness of Reiter s general solution to the frame problem based on the situation calculus [14] for a ....

....providing a semantic correspondence between the models selected by the entailment criterion and the models obtained from the underlying semantics. Additionally, in Section 5, we compare our methodology to Kartha s evaluation [6] of Reiter s general solution with respect to action logic semantics [4] and we assess the applicability of Reiter s solution to formalize database updates [16, 15] in Section 6. Finally, we present the conclusions and future work. 2 Reiter s General Solution Reiter [14] proposes a formalism to reason about action in first order logic. Building on work by Haas [5] ....

[Article contains additional citation context not shown here]

M. Gelfond and V. Lifschitz. Describing action and change by logic programs. In Joint International Conference and Symposium on Logic Programming, 1992.

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