M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of ICLP,p. 207--224, Santa Margherita Ligure, Italy, 1994. MIT Press.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....fragile, is more specific than a drop action, whose only condition is that a robot holds an object. Consequently, dropping a fragile object will cause the object to be broken. Specificity is incorporated into the equational logic approach using negation as failure and Clark s completion [10] In [37] it is shown that this extension can be used to correctly and completely implement the action description language A developed by Gelfond and Lifschitz [13] As planning problems formulated in A can also be translated into into the situation calculus and into a circumscriptive scheme (see [22] ....

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, editor, Proceedings of the International Conference on Logic Programming, pages 207--224. MIT Press, 1994. Received sometime

....to be sound relative to the semantics of A. The three translations discussed in this chapter were first reported in [Kartha, 1993] Translations from A into abductive logic programming in can be found in [Dung, 1993] and [Denecker and De Schreye, 1993] and into equational logic programming in [Thielscher, 1994b] If a theorem prover, or a query evaluation procedure, is available for the target language of such a translation, then it becomes possible to use the translation for the automation of reasoning about action. For example, the logic programming interpreter XOLDT [Chen and Warren, 1992] is put ....

....framework. Also, all actions are assumed to have determinisitic effects. Such expressive limitations of A have led researchers to enhance it in various ways. Dung [1993] proposed a relational version of A, in which fluents and actions may have arguments. In [Denecker and De Schreye, 1993] and [Thielscher, 1994b] dialects of A are outlined in which one can describe actions with nondeterministic effects. Baral and Gelfond [1993] extend A by an operator for the concurrent execution of a set of actions. The dialect of A defined in [Lifschitz, 1993b] provides symbols for time intervals. 3.7 Discussion ....

Michael Thielscher. Representing actions in equational logic programming. In Pascal Van Hentenryck, editor, Proc. ICLP-94, pages 207--224, 1994.

.... into the first one or into the application of R) 5 Detecting Termination Theorem 1 almost gives a proof theoretic treatment of Thielscher s algorithm in [14, 15] He there describes a treatment of ramification in which one first computes the direct e#ects of actions using the fluent calculus [13] (by [3] this is equivalent to non modal linear logic) and then applies a rewrite system to compute the ramification. We can obtain the same e#ect by applying Theorem 1 to inferences in which A is an input situation, B an output situation, and A # ( B # is an action. However, it generalises this ....

Michael Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, editor, Proceedings of the International Conference on Logic Programming (ICLP), pages 207--224. MIT Press, 1994.

....the language of abductive logic programming and by Turner [1994] into the language of disjunctive logic programming. 16 Other high level action description languages have been defined as approximate extensions of A; for example, Baral and Gelfond, 1993 ] Kartha and Lifschitz, 1994 ] Thielscher, 1994 ] Giunchiglia and Lifschitz, 1995 ] Giunchiglia et al. 1995 ] Baral et al. 1995 ] and [ Turner, 1997b ] The languages defined in [ Kartha and Lifschitz, 1994 ] and [ Giunchiglia et al. 1995 ] AR 0 and AR, respectively, are particularly important in the present context, since ....

Michael Thielscher. Representing actions in equational logic programming. In Proc. ICLP-94, pages 207--224, 1994.

....into logic programming was partial it was sound only for a restricted subset of the A domain descriptions and incomplete. Later sound and complete translations of A utilized extensions or variants of logic programming: abductive logic programming [DD93, Dun93] equational logic programming [Thi94], or disjunctive logic programming [Tur94] For the portion of AC that corresponds to A, we specify in this paper a translation into logic programming that is arguably simpler than any of those previously published, and does not require abduction or disjunction. Furthermore, the portion of AC that ....

....into logic programming was partial it was not sound for some consistent A domain descriptions and incomplete. Later sound and complete translations of consistent A utilized extensions or variants of logic programming: abductive logic programming [DD93, Dun93] equational logic programming [Thi94], or disjunctive logic programming [Tur94] For the portion of AC that corresponds to consistent A, our sound and complete translation 0 is arguably simpler than any of those previously published, and does not require abduction or disjunction. Furthermore, the portion of AC that we embed in ....

Michael Thielscher. Representing actions in equational logic programming. In Pascal Van Hentenryck, editor, Logic Programming: Proc. of the 11th Int'l Conference, pages 207--224. MIT Press, 1994.

.... either into the first one or into the application of SigmaR) Remark 5 Corollary 3 almost gives a proof theoretic treatment of Thielscher s algorithm in [30, 31] He there describes a treatment of ramification in which one first computes the direct effects of actions using the fluent calculus [29] (by [8] this is equivalent to non modal linear logic) and then applies a rewrite system to compute the ramification. We can obtain the same effect by applying Corollary 3 to inferences in which A is an input situation, B an output situation, and A 0 ( B 0 is an action. The proof of the ....

Michael Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, editor, Proceedings of the International Conference on Logic Programming (ICLP), pages 207--224. MIT Press, 1994.

....and then deploy such a definition explicitly, in straightforward fashion, to constrain more general model structures (encompassing more than an initial situation, action, and resulting situation) In [GL93] the high level action language A was introduced. Many of the subsequent action languages [BG93, KL94, Thi94, BGP95, GKL95, GL95, Thi95b, Tur96a] are essentially extensions of A. These languages share a situation calculus ontology. Next we briefly describe some of their main features and differences. In A actions are deterministic, always executable, and cannot be performed concurrently. Furthermore, fluents are propositional (that is, ....

....executable, and cannot be performed concurrently. Furthermore, fluents are propositional (that is, boolean valued) and there is no way to represent background knowledge of any kind. In AC [BG93] concurrent actions are allowed and actions are no longer required to be always executable. In AND [Thi94], actions may be nondeterministic. In the languages AR 0 and AR [KL94, GKL95, GKL97] actions may be nondeterministic and are not required to be always executable. More importantly, these languages allow the use of state constraints to express background knowledge. Also, these languages employ ....

[Article contains additional citation context not shown here]

Michael Thielscher. Representing actions in equational logic programming. In Pascal Van Hentenryck, editor, Logic Programming: Proc. of the 11th Int'l Conference, pages 207--224. MIT Press, 1994.

....particular, the approach developed in [26] is based on logic programming with an associated equational theory. Since its first formalization, this method has been extended into various directions, e.g. to handle objects [20] specificity [28] concurrent [3] as well as non deterministic actions [5, 45], and ramifications [46] Moreover, its relation to the high level specification languages A [16] and the Ego World Semantics [42] were clarified [45, 44] Although these results illustrate the expressiveness of the equational logic programming approach (ELP, for short) in principle, the ....

.... has been extended into various directions, e.g. to handle objects [20] specificity [28] concurrent [3] as well as non deterministic actions [5, 45] and ramifications [46] Moreover, its relation to the high level specification languages A [16] and the Ego World Semantics [42] were clarified [45, 44]. Although these results illustrate the expressiveness of the equational logic programming approach (ELP, for short) in principle, the applicability of concrete proof strategies such as Prolog has not yet been assessed. A major difficulty is caused by the use of an underlying equational theory, ....

Michael Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, editor, Proceedings of the International Conference on Logic Programming (ICLP), pages 207--224, Santa Margherita Ligure, Italy, June 1994. MIT Press.

....fragile, is more specific than a drop action, whose only condition is that a robot holds an object. Consequently, dropping a fragile object will cause the object to be broken. Specificity is incorporated into the equational logic approach using negation as failure and Clark s completion [10] In [37] it is shown that this extension can be used to correctly and completely implement the action description language A developed by Gelfond and Lifschitz [13] As planning problems formulated in A can also be translated into into the situation calculus and into a circumscriptive scheme (see [22] ....

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, editor, Proceedings of the International Conference on Logic Programming, pages 207--224. MIT Press, 1994. Received sometime

No context found.

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of ICLP,p. 207--224, Santa Margherita Ligure, Italy, 1994. MIT Press.

No context found.

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of ICLP, p. 207--224, Santa Margherita Ligure, Italy, June 1994. MIT Press.

No context found.

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of ICLP, p. 207--224, Santa Margherita Ligure, Italy, June 1994. MIT Press.

No context found.

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, editor, Proceedings of the International Conference on Logic Programming (ICLP), pages 207--225, Santa Margherita Ligure, Italy, 1994. MIT Press.

No context found.

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of the ICLP, 1994.

....of action descriptions, we use a simple and straightforwardly automated transformation, which creates exactly the four action descriptions (9) 12) of Section 2 given the e proposition (23) 6 Due to lack of space, we omit a formal description of this transformation here. It can be found in [30]. Reasoning about the past is mainly based on finding consistent explanations for observations. Recall that the actions for the Fragile Object domain were designed such that the application of an action to a consistent situation yields a consistent situation. Now, however, we have to ensure that ....

....true in the initial situation. This is not necessary in general of course, since leaving the initial situation totally unspecified, the various answer substitutions to a query such as #X,Y. causes (X, drop] broken #Y ) should give us a hint of what might have been true at the beginning. In [30] it is shown that the ideas sketched above can be used as a sound and complete implementation of the action description language of Gelfond and Lifschitz. This makes our approach to reason about actions and change comparable to various other approaches which were also related to this language ....

M. Thielscher. Representing Actions in Equational Logic Programming. 1993. (forthcoming paper).

....or uncertainty, i.e. the existence of alternative and coincidental effects, there should be a unique applicable description for a method to each consistent object, leading to a still consistent object. Such an ideal set of object descriptions can be obtained in the Broken Item domain (see also [54]) We have already considered Methods (2) and (3) These two methods, however, do not yet completely specify the Broken Item domain. For instance, 3) is inherited by the class of intact objects. Its application would lead to the inconsistency fjintact ; fragile; brokenjg , where the item at hand ....

....method is applied to a consistent object then the resulting object is also consistent. A formal proof for this set of actions being consistency preserving is analogous to the respective proofs for the Blocksworld domain presented in [28] and can be extracted from a general result presented in [54]. So far we have formally defined objects and methods. However, reasoning about change usually deals with situations and actions (e.g. 41] It would be an interesting paper on itself to discuss the similarities and differences of situationbased planning and object oriented programming. As far as ....

[Article contains additional citation context not shown here]

M. Thielscher. Representing Actions in Equational Logic Programming. In P. V. Hentenryck, editor, Proceedings of the International Conference on Logic Programming (ICLP), pages 207--224, Santa Margherita Ligure, Italy, June 1994. MIT Press.

....their comparison, and an assessment of the range of their applicability. Such semantics have recently been developed for the discrete case (Gelfond Lifschitz 1993; Sandewall 1994; Thielscher 1995) and successfully applied to concrete calculi, e.g. Kartha 1993; Doherty Lukaszewicz 1994; Thielscher 1994). However, neither of these formalisms is suitable for calculi dealing with continuous processes. The Action Description Language (Gelfond Lifschitz 1993) is based on the concept of single step actions and does not include a notion of time. In (Sandewall 1994) the duration of actions is not ....

Thielscher, M. 1994. Representing actions in equational logic programming. In Hentenryck, P. V., ed., Proc. of the Int.'l Conf. on Logic Programming, 207--224. Santa Margherita Ligure, Italy: MIT Press.

.... way, which is in favorable contrast to the traditional way of explaining new approaches with reference to a few standard examples, such as some in the blocksworld or the famous Yale Shooting Scenario and its enhancements [7, 16, 17] To this end, A was translated into several formalisms [7, 5, 14, 4, 19]. In [1] a sound but, unfortunately, incomplete encoding of AC using extended logic programs following the lines of [7] was presented. In this paper, we extend the work [19] and show how an approach based on equational logic programming (ELP) 10, 9] can be used as a sound and even complete ....

....Shooting Scenario and its enhancements [7, 16, 17] To this end, A was translated into several formalisms [7, 5, 14, 4, 19] In [1] a sound but, unfortunately, incomplete encoding of AC using extended logic programs following the lines of [7] was presented. In this paper, we extend the work [19] and show how an approach based on equational logic programming (ELP) 10, 9] can be used as a sound and even complete method for encoding AC and A C . ELP is a deductive approach using first order logic for describing actions. Similar to A and AC , the effects of actions are described by ....

[Article contains additional citation context not shown here]

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of ICLP,p. 207--224, Santa Margherita Ligure, Italy, 1994. MIT Press.

No context found.

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of the ICLP, 1994.

....and an assessment of the range of their applicability. Such semantics have recently been developed for the discrete case [ Gelfond and Lifschitz, 1993; Sandewall, 1994; Thielscher, 1995 ] and successfully applied to concrete calculi, e.g. Kartha, 1993; Doherty and Lukaszewicz, 1994; Thielscher, 1994 ] However, neither of these formalisms is suitable for calculi dealing with continuous processes. The Action Description Language [ Gelfond and Lifschitz, 1993 ] is based on the concept of single step actions and does not include a notion of time. In [ Sandewall, 1994 ] the duration of ....

Michael Thielscher. Representing actions in equational logic programming. In P. Van Hentenryck, editor, Proceedings of the International Conference on Logic Programming (ICLP), pages 207--224, Santa Margherita Ligure, Italy, June 1994. MIT Press.

....of action descriptions, we use a simple and straightforwardly automated transformation, which creates exactly the four action descriptions (9) 12) of Section 2 given the e proposition (23) 6 Due to lack of space, we omit a formal description of this transformation here. It can be found in [30]. Reasoning about the past is mainly based on finding consistent explanations for observations. Recall that the actions for the Fragile Object domain were designed such that the application of an action to a consistent situation yields a consistent situation. Now, however, we have to ensure that ....

....true in the initial situation. This is not necessary in general of course, since leaving the initial situation totally unspecified, the various answer substitutions to a query such as 9X; Y: causes (X; drop] broken ffi Y ) should give us a hint of what might have been true at the beginning. In [30] it is shown that the ideas sketched above can be used as a sound and complete implementation of the action description language of Gelfond and Lifschitz. This makes our approach to reason about actions and change comparable to various other approaches which were also related to this language ....

M. Thielscher. Representing Actions in Equational Logic Programming. 1993. (forthcoming paper).

....range of their applicability. Such semantics have recently been developed for the discrete case [Gelfond Lifschitz, 1993; Sandewall, 1994; Thielscher, 1995] and successfully applied to concrete calculi, e.g. Kartha, 1993; Dung, 1993; Denecker de Schreye, 1993; Doherty Lukaszewicz, 1994; Thielscher, 1994; Kartha Lifschitz, 1994] However, neither of these formalisms is suitable for calculi dealing with continuous processes. The Action Description Language [Gelfond Lifschitz, 1993] is based on the concept of singlestep actions and does not include a notion of time. In [Sandewall, 1994] the ....

Thielscher, M. 1994. Representing actions in equational logic programming. In Hentenryck, P. V., ed., Proceedings of the International Conference on Logic Programming (ICLP), 207--224. Santa Margherita Ligure, Italy: MIT Press.

....Programming (ELP) Holldobler and Schneeberger, 1990 ] In contrast to Strips, this approach has recently turned out to have a wide range of applicability as regards general aspects of topical interest, e.g. postdiction problems, reasoning about nondeterministic and concurrent actions, etc. Thielscher, 1994; Bornscheuer and Thielscher, 1994 ] Moreover, this method is provably equivalent to a modification of the Connection Method designed for planning problems [ Bibel, 1986 ] and to an approach to planning based on Linear Logic [ Masseron et al. 1990 ] see [ Gro e et al. 1995 ] The rest of ....

....Schneeberger, 1990 ] In contrast to Strips, this approach has recently turned out to have a wide range of applicability as regards general aspects of topical interest, e.g. postdiction problems, reasoning about nondeterministic and concurrent actions, etc. Thielscher, 1994; Bornscheuer and Thielscher, 1994 ] Moreover, this method is provably equivalent to a modification of the Connection Method designed for planning problems [ Bibel, 1986 ] and to an approach to planning based on Linear Logic [ Masseron et al. 1990 ] see [ Gro e et al. 1995 ] The rest of this paper is organized as follows. ....

[Article contains additional citation context not shown here]

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of ICLP, p. 207--224, Santa Margherita Ligure, Italy, June 1994. MIT Press.

....whose causal laws propose mutually exclusive effects: Instead of declaring such situations impossible, which is the standard proposal in literature (e.g. Lin and Shoham, 1992; Baral and Gelfond, 1993; Gro e, 1994 ] we take only the disputed effects as uncertain (c.f. Bornscheuer and Thielscher, 1994 ] The reader should be aware of the purpose of this paper, which is unusual in so far as it merely consists of definitions rather than describing concrete results. We propose a formal framework to specify and to reason about dynamic systems. Thus, our intention is similar to the purpose of the ....

....to so called nondeterministic dynamic systems. Nondeterminism occurs when uncertainty about the successor state exists even in case the current state is completely known. This is reflected in the following definition, where the causal model consists of a relation on pairs of states (see, e.g. Thielscher, 1994 ] instead of a function as in Definition 1: Definition 9 A nondeterministic, propositional dynamic system is a pair (F ; Phi) consisting of a set of fluents F and a relation Phi 2 F Theta 2 F . Given a state s F , each s 0 such that (s; s 0 ) 2 Phi is called a possible ....

[Article contains additional citation context not shown here]

M. Thielscher. Representing Actions in Equational Logic Programming. In P. Van Hentenryck, ed., Proc. of ICLP, p. 207--224, Santa Margherita Ligure, Italy, June 1994. MIT Press.

....and Lifschitz, 1993 ] the Ego World Semantics [ Sandewall, 1994 ] and the framework presented in [ Thielscher, 1995 ] These approaches are considered prime candidates for being enhanced by the concept of causal relationships. In case of A , this should be based on the dialect called AND [ Thielscher, 1994b ] which includes the notion of non determinism, here needed if more than a single successor state exists. The resulting extension of the Action Description Language would constitute an alternate to the variant presented in [ Kartha and Lifschitz, 1994 ] which handles ramifications on the ....

.... from being closely related, in its basic form, to the Linear Connection Method [ Bibel, 1986 ] and reasoning about actions based on Linear Logic [ Girard, 1987; Masseron et al. 1993 ] has shown a wide range of applicability, e.g. regarding postdiction problems and non deterministic actions [ Thielscher, 1994b ] reasoning about counterfactual action sequences [ Thielscher, 1994a ] or concurrent actions in conjunction with (locally) inconsistent specifications [ Bornscheuer and Thielscher, 1994 ] Thus, a main goal of future research consists in combining all these results, each of which focuses on ....

Michael Thielscher. Representing actions in equational logic programming. In P. Van Hentenryck, editor, Proceedings of the International Conference on Logic Programming (ICLP), pages 207--224, Santa Margherita Ligure, Italy, June 1994. MIT Press.

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