M. Thielscher. The logic of dynamic systems. In C. S. Mellish, editor, Proceedings of the International Joint Conference on Artificial Intelligence, pp. 1965--1962, Montreal, 1995. Morgan Kaufmann.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... To incorporate causal domain laws into the basic transition function of section 3 we define it as before except Definition 15 s 0 = trans(s 00 ; L; 0) where s 00 is computed like s 0 in Definition 6 L is the set of causal laws An interesting extension to this concept proposed in [Thi95] is to define a partial order on the set of causal laws that allows to apply only the most specific applicable laws in a state s. While the definition is easy it lies beyond the scope of this paper. 6 Summary and outlook We have motivated and presented a basic formal model for planning in ....

....real world problems allow for or even need concurrency, especially in the field of planning for multi agent systems. Extensions of the semantics allow to model increasingly complex situations, operators and their concurrent application. For all of 5 This part of our work is mainly inspired by [Thi95] 6 See [KG99] for a similar point of view. these extensions reasonable semantics have been defined that above all will allow automatic planning for concurrent domains specified in the language BTPL. Deliberately, we did not describe any concrete planning algorithm in this paper: we believe ....

Michael Thielscher. The logic of dynamic systems. In Proc. of IJCAI '95, 1995.

....signature with respect to which they are defined. 99 The formulas :Up(Left) 0 :Up(Right) 0 Raise(Left) 0 :Raise(Right) 0 oe Spilled 1 :Spilled 0 Raise(Left) 0 Raise(Right) 0 oe :Spilled 1 are consequences of D 7:1 . 5 3 In [ Gelfond et al. 1991b ] Baral and Gelfond, 1993 ] and [ Thielscher, 1995b ] the Soup domain is described essentially as follows: i) the action of raising either side of the bowl causes the soup to be spilled, but (ii) assuming the soup is not already spilled, raising both sides of the bowl concurrently causes it not to be spilled. The formal renderings of statements ....

Michael Thielscher. On the logic of dynamic systems. In Proc. of IJCAI-95, pages 1956--1962, 1995.

....have been performed, what has been observed, and how the world should behave, traditionally stated as formulae in some logic. Then, a property of developments is entailed by a scenario if it holds in every development in the scenario. We represent the execution of actions by features (like in [13]) e.g. an action shoot is represented as a propositional feature which is true at time points when the action is invoked, and false otherwise (Sandewall [11] uses actions with duration, so then we get two features: one for the invocation and one for the ending of the action) Effects of actions ....

Michael Thielscher, `The logic of dynamic systems', in Proceedings of the International Joint Conference on Artificial Intelligence, (1995). 14

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M. Thielscher. The logic of dynamic systems. In C. S. Mellish, editor, Proceedings of the International Joint Conference on Artificial Intelligence, pp. 1965--1962, Montreal, 1995. Morgan Kaufmann.

....achieves this: Event occurrences are identified as fluents. That is to say, each state of the world is also characterized by the events which currently happen, if any. By this we adapt the actions as fluents paradigm, which has been propagated, for instance, in [ Lin and Shoham, 1992; Groe, 1994; Thielscher, 1995 ] To emphasize this shift, we will write event fluents using the symbol happens instead of Happens . Relations among events, like the one formalized in equation (2) can now be considered state constraints, which supposedly hold in all states, e.g. 5 happens(lleft) j :happens(lright) oe ....

.... 1) s (25) Possible(State(S 0 ) 26) The extended assumption of uniqueness of names, EUNA, completes the axiomatization. Its definition relies on a complete AC1 unification algorithm (see, e.g. Burckert et al. 1988 ] Set EUNA comprises the following equational axioms [ Holldobler and Thielscher, 1995 ] 20 1. The axioms AC1 and the standard equality axioms, viz. x ffi y) ffi z = x ffi (y ffi z) x ffi y = y ffi x x ffi ; x x = x x = y oe y = x x = y y = z oe x = z x i = y oe f(x 1 ; x i ; x n ) f(x 1 ; y; x n ) x i = y oe [P (x 1 ; x i ; ....

Michael Thielscher. The logic of dynamic systems. In C. S. Mellish, editor, Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), pages 1956--1962, Montreal, Canada, August 1995. Morgan Kaufmann.

....if faced with miraculous, i.e. inexplicable, disqualifications. The formal account of the qualification problem presented in this paper satisfies all of these requirements. In the second part, we develop, on the basis of the fluent calculus [ Holldobler and Schneeberger, 1990; Holldobler and Thielscher, 1995 ] an action calculus which includes a proper treatment of abnormal disqualifications. Our encoding builds on the fluent calculus based solution to the ramification problem developed in [ Thielscher, 1997 ] Since the qualification problem requires some sort of nonmonotonic feature, we employ ....

....problem, the second part of the paper is devoted to the development of an action calculus which is capable of handling abnormal action disqualifications. Our encoding employs the representation technique underlying the fluent calculus [ Holldobler and Schneeberger, 1990; Holldobler and Thielscher, 1995 ] We begin by repeating the fluent calculus based formalization of causal relationships developed in [ Thielscher, 1997 ] Section 4.1) In Section 4.2, this calculus is extended by a suitable encoding of observations. Finally and as a solution to the qualification problem, in Section 4.3 we ....

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Michael Thielscher. The logic of dynamic systems. In C. S. Mellish, editor, Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), pages 1956--1962, Montreal, Canada, August 1995. Morgan Kaufmann.

....The underlying principles of our theory, however, are sufficiently fundamental and general to not depend on this specific language. Thus these principles could equally well be employed in other, more elaborated formal theories of actions like, e.g. Gelfond and Lifschitz, 1993; Sandewall, 1994; Thielscher, 1995 ] in view of the qualification problem. Likewise, existing action calculi may be enhanced on this basis in order that they become capable of dealing with abnormal action disqualifications. As an example, we have sketched a way to embed the fluent calculus in an appropriate nonmonotonic theory. ....

M. Thielscher. The logic of dynamic systems. In C. Mellish, ed., Proc. of the IJCAI, p. 1956--1962, Montreal, 1995.

....exploited to define a high level action semantics serving as basis for a formal justification of such calculi, their comparison, 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 ....

....include a notion of time. In [ Sandewall, 1994 ] the duration of actions is not fixed, but equidistant discretization is assumed and state transitions only occur when actions are executed otherwise the world description is assumed to remain stable. While in contrast the approach developed in [ Thielscher, 1995 ] allows for user independent events to cause state transitions, again equidistant discretization is assumed. In this paper, we propose a new semantics for reasoning about continuous change which allows for varying temporal distances between state transitions. The described system may have ....

[Article contains additional citation context not shown here]

Michael Thielscher. The logic of dynamic systems. In C. S. Mellish, editor, Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), pages 1956--1962, Montreal, Canada, August 1995. Morgan Kaufmann.

....into different approaches designed for reasoning about dynamic systems, actions, and change allows to compare the possibilities and limitations of these approaches in a precise and uniform way. As argued in, e.g. Gelfond and Lifschitz, 1993; Sandewall, 1993; Sandewall, 1994; Thielscher, 1994; Thielscher, 1995b ] doing this is in favorable contrast to the traditional way of justifying new approaches with reference to a few standard examples such as the blocksworld or the famous Yale Shooting Scenario and its enhancements. To this end, translations of A and some of its extensions, for instance, into ....

Michael Thielscher. The logic of dynamic systems. In C. S. Mellish, editor, Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), pages 1956--1962, Montreal, Canada, August 1995. Morgan Kaufmann.

....achieves this: Event occurrences are identified as fluents. That is to say, each state of the world is also characterized by the events which currently happen, if any. By this we adapt the actions as fluents paradigm, which has been propagated, for instance, in [ Lin and Shoham, 1992; Gro e, 1994; Thielscher, 1995 ] To emphasize this shift, we will write event fluents using the symbol happens instead of Happens . Relations among events, like the one formalized in equation (2) can now be considered state constraints, which supposedly hold in all states, e.g. 5 happens(lleft) j :happens(lright) oe ....

M. Thielscher. The logic of dynamic systems. In C. S. Mellish, editor, Proceedings of the IJCAI, pages 1956--1962, Montreal, Canada, August 1995. Morgan Kaufmann.

....Section 7. In the second part of the paper, Section 6, we integrate the concept of causal relationships into a particular action calculus which is based on reifying entire state descriptions and which employs the logic programming paradigm [ Holldobler and Schneeberger, 1990; Holldobler and Thielscher, 1995 ] While for sake of simplicity states are described via a set of propositional constants in the first part (see Section 2) the calculus itself employs more complex a notion of fluent, which comes along with fluent formulas involving quantifications. The extended calculus will be proved sound ....

....problem compared to others, the second part of the paper is devoted to the development of a suitable, concrete calculus. This calculus will be based on the logic programming paradigm. More precisely, we adapt and extend a method described in [ Holldobler and Schneeberger, 1990; Holldobler and Thielscher, 1995 ] which applies the concept of reification to entire states, i.e. each of which is formally represented as single term and, thus, is manipulable by means of program clauses. The adequate treatment of these terms requires a (domain independent) equational theory, which, essentially, formalizes ....

[Article contains additional citation context not shown here]

Michael Thielscher. The logic of dynamic systems. In C. S. Mellish, editor, Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), pages 1956--1962, Montreal, Canada, August 1995. Morgan Kaufmann.

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