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50
Temporal Reasoning in the Situation Calculus
, 1994
"... A fundamental problem in Knowledge Representation is the design of a logical language to express theories about actions and change. One of the most prominent proposals for such a language is John McCarthy's situation calculus, a formalism which views situations as branching towards the future. The s ..."
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Cited by 127 (11 self)
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A fundamental problem in Knowledge Representation is the design of a logical language to express theories about actions and change. One of the most prominent proposals for such a language is John McCarthy's situation calculus, a formalism which views situations as branching towards the future. The situation calculus has been criticized for imposing severe representational limitations. For example, actions cannot be concurrent, properties change discretely, etc. In this thesis we show that many of these limitations can be overcome. Our work builds upon the discrete situation calculus and on Reiter's monotonic solution to the frame problem. A limitation of Reiter's approach is that it does not allow for state constraints. However, Lin and Reiter have made progress by providing a correctness criterion by which one can determine if an axiomatization can be said to solve the frame problem for theories that include state constraints.
The Paradoxical Success of Fuzzy Logic
 IEEE Expert
, 1993
"... Applications of fuzzy logic in heuristic control have been highly successful, but which aspects of fuzzy logic are essential to its practical usefulness? This paper shows that an apparently reasonable version of fuzzy logic collapses mathematically to twovalued logic. Moreover, there are few if any ..."
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Cited by 69 (1 self)
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Applications of fuzzy logic in heuristic control have been highly successful, but which aspects of fuzzy logic are essential to its practical usefulness? This paper shows that an apparently reasonable version of fuzzy logic collapses mathematically to twovalued logic. Moreover, there are few if any published reports of expert systems in realworld use that reason about uncertainty using fuzzy logic. It appears that the limitations of fuzzy logic have not been detrimental in control applications because current fuzzy controllers are far simpler than other knowledgebased systems. In the future, the technical limitations of fuzzy logic can be expected to become important in practice, and work on fuzzy controllers will also encounter several problems of scale already known for other knowledgebased systems. 1
A Circumscriptive Calculus of Events
 Artificial Intelligence
, 1995
"... A calculus of events is presented in which domain constraints, concurrent events, and events with nondeterministic effects can be represented. The paper offers a nonmonotonic solution to the frame problem for this formalism that combines two of the techniques developed for the situation calculus, ..."
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Cited by 68 (11 self)
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A calculus of events is presented in which domain constraints, concurrent events, and events with nondeterministic effects can be represented. The paper offers a nonmonotonic solution to the frame problem for this formalism that combines two of the techniques developed for the situation calculus, namely causal and statebased minimisation. A theorem is presented which guarantees that temporal projection will not interfere with minimisation in this solution, even in domains with ramifications, concurrency, and nondeterminism. Finally, the paper shows how the formalism can be extended to cope with continuous change, whilst preserving the conditions for the theorem to apply. 1 Introduction The frame problem was first described by McCarthy and Hayes in the Sixties [23], and has occupied the thoughts of AI researchers ever since. In a nutshell, the problem is this: if we deploy classical logic in a straightforward way to describe the effects of actions, we have to represent explicitl...
Representing Continuous Change in The Event Calculus
 PROCEEDINGS ECAI 90, PAGES 598603
, 1990
"... The Event Calculus of Kowalski and Sergot only deals with discrete change. This paper introduces a simplified version of the Event Calculus and extends it to deal with continuous change, as in the height of a falling object or the level of liquid in a filling vessel. The idea of autotermination i ..."
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Cited by 64 (1 self)
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The Event Calculus of Kowalski and Sergot only deals with discrete change. This paper introduces a simplified version of the Event Calculus and extends it to deal with continuous change, as in the height of a falling object or the level of liquid in a filling vessel. The idea of autotermination is introduced. A period of continuous change autoterminates if it brings about the event which terminates it. For example, when the increasing level of water in a sink reaches the overflow, it ceases to increase. The formulation is applied to a simple example with liquid filling a sink, and to a more complicated one with many tanks discharging liquid into another tank.
The Event Calculus in Classical Logic  Alternative Axiomatisations
, 1999
"... We present several alternative classical logic axiomatisations of the Event Calculus, a narrative based formalism for reasoning about actions and change. We indicate the range of applicability and key characteristics of each alternative formulation. ..."
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Cited by 45 (1 self)
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We present several alternative classical logic axiomatisations of the Event Calculus, a narrative based formalism for reasoning about actions and change. We indicate the range of applicability and key characteristics of each alternative formulation.
Some alternative formulations of the event calculus
 Computer Science; Computational Logic; Logic programming and Beyond
, 2002
"... Abstract. The Event Calculus is a narrative based formalism for reasoning about actions and change originally proposed in logic programming form by Kowalski and Sergot. In this paper we summarise how variants of the Event Calculus may be expressed as classical logic axiomatisations, and how under ce ..."
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Cited by 38 (2 self)
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Abstract. The Event Calculus is a narrative based formalism for reasoning about actions and change originally proposed in logic programming form by Kowalski and Sergot. In this paper we summarise how variants of the Event Calculus may be expressed as classical logic axiomatisations, and how under certain circumstances these theories may be reformulated as “action description language ” domain descriptions using the Language E. This enables the classical logic Event Calculus to inherit various provably correct automated reasoning procedures recently developed for E. 1
Towards More Realistic LogicBased Robot Controllers in . . .
, 2000
"... this paper, we show how these issues can be dealt with in the GOLOG frameworkby proposing appropriate extensions of the language. ..."
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Cited by 32 (10 self)
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this paper, we show how these issues can be dealt with in the GOLOG frameworkby proposing appropriate extensions of the language.
Logic programming for robot control
 Proc. 14th International Joint Conf. on Artificial Intelligence (IJCAI95
, 1995
"... This paper proposes logic programs as a specification for robot control. These provide a formal specification of what an agent should do depending on what it senses, and its previous sensory inputs and actions. We show how to axiomatise reactive agents, events as an interface between continuous and ..."
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Cited by 32 (7 self)
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This paper proposes logic programs as a specification for robot control. These provide a formal specification of what an agent should do depending on what it senses, and its previous sensory inputs and actions. We show how to axiomatise reactive agents, events as an interface between continuous and discrete time, and persistence, as well as axiomatising integration and differentiation over time (in terms of the limit of sums and differences). This specification need not be evaluated as a Prolog program; we use can the fact that it will be evaluated in time to get a more efficient agent. We give a detailed example of a nonholonomic maze travelling robot, where we use the same language to model both the agent and the environment. One of the main motivations for this work is that there is a clean interface between the logic programs here and the model of uncertainty embedded in probabilistic Horn abduction. This is one step towards building a decisiontheoretic planning system where the output of the planner is a plan suitable for actually controlling a robot. 1
Modelling mixed discretecontinuous domains for planning
 Journal of Artificial Intelligence Research
, 2006
"... In this paper we present pddl+, a planning domain description language for modelling mixed discretecontinuous planning domains. We describe the syntax and modelling style of pddl+, showing that the language makes convenient the modelling of complex timedependent effects. We provide a formal semant ..."
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Cited by 30 (7 self)
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In this paper we present pddl+, a planning domain description language for modelling mixed discretecontinuous planning domains. We describe the syntax and modelling style of pddl+, showing that the language makes convenient the modelling of complex timedependent effects. We provide a formal semantics for pddl+ by mapping planning instances into constructs of hybrid automata. Using the syntax of HAs as our semantic model we construct a semantic mapping to labelled transition systems to complete the formal interpretation of pddl+ planning instances. An advantage of building a mapping from pddl+ to HA theory is that it forms a bridge between the Planning and Real Time Systems research communities. One consequence is that we can expect to make use of some of the theoretical properties of HAs. For example, for a restricted class of HAs the Reachability problem (which is equivalent to Plan Existence) is decidable. pddl+ provides an alternative to the continuous durative action model of pddl2.1, adding a more flexible and robust model of timedependent behaviour.
Let's Plan It Deductively
 Artificial Intelligence
, 1997
"... The paper describes a transition logic, TL, and a deductive formalism for it. It shows how various important aspects (such as ramification, qualification, specificity, simultaneity, indeterminism etc.) involved in planning (or in reasoning about action and causality for that matter) can be modell ..."
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Cited by 28 (0 self)
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The paper describes a transition logic, TL, and a deductive formalism for it. It shows how various important aspects (such as ramification, qualification, specificity, simultaneity, indeterminism etc.) involved in planning (or in reasoning about action and causality for that matter) can be modelled in TL in a rather natural way. (The deductive formalism for) TL extends the linear connection method proposed earlier by the author by embedding the latter into classical logic, so that classical and resourcesensitive reasoning coexist within TL. The attraction of a logical and deductive approach to planning is emphasized and the state of automated deduction briefly described. 1 Introduction Artificial Intelligence (AI, or Intellectics [Bib92a]) aims at creating artificial (or computational [PMG98]) intelligence. Were there no natural intelligence, the sentence would be meaningless to us. Hence understanding natural intelligence by necessity has always been among the goals of Intel...