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27
Actions and Events in Interval Temporal Logic
 Journal of Logic and Computation
, 1994
"... We present a representation of events and action based on interval temporal logic that is significantly more expressive and more natural than most previous AI approaches. The representation is motivated by work in natural language semantics and discourse, temporal logic, and AI planning and plan rec ..."
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Cited by 233 (7 self)
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We present a representation of events and action based on interval temporal logic that is significantly more expressive and more natural than most previous AI approaches. The representation is motivated by work in natural language semantics and discourse, temporal logic, and AI planning and plan recognition. The formal basis of the representation is presented in detail, from the axiomatization of time periods to the relationship between actions and events and their effects. The power of the representation is illustrated by applying it to the axiomatization and solution of several standard problems from the AI literature on action and change. An approach to the frame problem based on explanation closure is shown to be both powerful and natural when combined with our representational framework. We also discuss features of the logic that are beyond the scope of many traditional representations, and describe our approach to difficult problems such as external events and simultaneous action...
Monotonic Solution of the Frame Problem in the Situation Calculus: An Efficient Method for Worlds with Fully Specified Actions
 Knowledge Representation and Defeasible Reasoning
, 1990
"... . The paper is concerned with the succinct axiomatization and ecient deduction of nonchange, within McCarthy and Hayes' Situation Calculus. The idea behind the proposed approach is this: suppose that in a room containing a man, a robot and a cat as the only potential agents, the only action ta ..."
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Cited by 145 (3 self)
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. The paper is concerned with the succinct axiomatization and ecient deduction of nonchange, within McCarthy and Hayes' Situation Calculus. The idea behind the proposed approach is this: suppose that in a room containing a man, a robot and a cat as the only potential agents, the only action taken by the man within a certain time interval is to walk from one place to another, while the robot's only actions are to pick up a box containing the (inactive) cat and carry it from its initial place to another. We wish to prove that a certain object (such as the cat, or the doormat) did not change color. We reason that the only way it could have changed color is for the man or the robot to have painted or dyed it. But since these are not among the actions which actually occurred, the color of the object is unchanged. Thus we need no frame axioms to the eect that walking and carrying leave colors unchanged (which is in general false in multiagent worlds), and no default schema that properties change only when we can prove they do (which is in general false in incompletely known worlds). Instead we use explanationclosure axioms specifying all primitive actions which can produce a given type of change within the setting of interest. A method similar to this has been proposed by Andrew Haas for singleagent, serial worlds. The contribution of the present paper lies in 1 showing (1) that such methods do indeed encode nonchange succinctly, (2) are independently motivated, (3) can be used to justify highly ecient methods of inferring nonchange, specically the \sleeping dog" strategy of STRIPS, and (4) can be extended to simple multiagent worlds with concurrent actions. An ultimate limitation may lie in the lack of a uniform strategy for deciding what ...
Prediction is Deduction but Explanation is Abduction
 Proceedings IJCAI 89
, 1989
"... This paper presents an approach to temporal reasoning in which prediction is deduction but explanation is abduction. It is argued that all causal laws should be expressed in the natural form effect if cause. Any given set of laws expressed in this way can be used for both forwards projection (predic ..."
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Cited by 139 (11 self)
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This paper presents an approach to temporal reasoning in which prediction is deduction but explanation is abduction. It is argued that all causal laws should be expressed in the natural form effect if cause. Any given set of laws expressed in this way can be used for both forwards projection (prediction) and backwards projection (explanation), but abduction must be used for explanation whilst deduction is used for prediction. The approach described uses a shortened form of Kowalski and Sergot's Event Calculus and incorporates the assumption that properties known to hold must have explanations in terms of events. Using abduction to implement this assumption results in a form of default persistence which correctly handles problems which have troubled other formulations. A straightforward extension to SLD resolution is described which implements the abductive approach to explanation, and which complements the wellunderstood deductive methods for prediction. Introduction Temporal reason...
Narratives in the Situation Calculus
, 1994
"... A narrative is a course of real events about which we might have incomplete information. Formalisms for reasoning about action may be broadly divided into those which are narrativebased, such as the Event Calculus of Kowalski and Sergot, and those which reason on the level of hypothetical sequences ..."
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Cited by 77 (5 self)
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A narrative is a course of real events about which we might have incomplete information. Formalisms for reasoning about action may be broadly divided into those which are narrativebased, such as the Event Calculus of Kowalski and Sergot, and those which reason on the level of hypothetical sequences of actions, in particular the Situation Calculus. This paper bridges the gap between these types of formalism by supplying a technique for linking incomplete narrative descriptions to Situation Calculus domain formulae written in the usual style using a Result function. Particular attention is given to actions with duration and overlapping actions. By illuminating the relationship between these two different styles of representation, the paper moves us one step closer to a full understanding of the space of all possible formalisms for reasoning about action. Introduction The Situation Calculus [15] is one of A.I.'s oldest and best understood formalisms for representing change, but it has of...
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...
A Simple Solution to the Yale Shooting Problem
, 1989
"... Most of the solutions proposed to the Yale shooting problem have either introduced new nonmonotonic reasoning methods (generally involving temporal priorities) or completely reformulated the domain axioms to represent causality explicitly. This paper presents a new solution based on the idea that si ..."
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Cited by 51 (3 self)
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Most of the solutions proposed to the Yale shooting problem have either introduced new nonmonotonic reasoning methods (generally involving temporal priorities) or completely reformulated the domain axioms to represent causality explicitly. This paper presents a new solution based on the idea that since the abnormality predicate takes a situational argument, it is important for the meanings of the situations to be held constant across the various models being compared. This is accomplished by a simple change in circumscription policy: when Ab is circumscribed, Result (rather than Holds) is allowed to vary. In addition, we need an axiom ensuring that every consistent situation is included in the domain of discourse. Ordinary circumscription will then produce the intuitively correct answer. Beyond its conceptual simplicity, the solution proposed here has additional advantages over the previous approaches. Unlike the approach that uses temporal priorities, it can support reasoning backwar...
Provably Correct Theories of Action
, 1991
"... We investigate logical formalization of the effects of actions in the situation calculus. We propose a formal criterion against which to evaluate theories of deterministic actions. We show how the criterion provides us a formal foundation upon which to tackle the frame problem, as well as its varian ..."
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Cited by 46 (1 self)
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We investigate logical formalization of the effects of actions in the situation calculus. We propose a formal criterion against which to evaluate theories of deterministic actions. We show how the criterion provides us a formal foundation upon which to tackle the frame problem, as well as its variant in the context of concurrent actions. Our main technical contributions are in formulating a wide class of monotonic causal theories that satisfy the criterion, and showing that each such theory can be reformulated succinctly in circumscription. 1 1 Introduction The histories of the frame problem [18], and of the particular Yale Shooting Problem (YSP) which has become its best known illustration [6], have followed a disturbing pattern. The frame problem itself, although introduced in the context of formalizing common sense, was never formally defined, and was only illustrated through suggestive examples. This is an initial disturbing factor. A second disturbing factor is that, despite the ...
Active Logics: A Unified Formal Approach to Episodic Reasoning
"... Artificial intelligence research falls roughly into two categories: formal and implementational. This division is not completely firm: there are implementational studies based on (formal or informal) theories (e.g., CYC, SOAR, OSCAR), and there are theories framed with an eye toward implementabili ..."
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Cited by 35 (2 self)
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Artificial intelligence research falls roughly into two categories: formal and implementational. This division is not completely firm: there are implementational studies based on (formal or informal) theories (e.g., CYC, SOAR, OSCAR), and there are theories framed with an eye toward implementability (e.g., predicate circumscription). Nevertheless, formal /theoretical work tends to focus on very narrow problems (and even on very special cases of very narrow problems) while trying to get them "right" in a very strict sense, while implementational work tends to aim at fairly broad ranges of behavior but often at the expense of any kind of overall conceptually unifying framework that informs understanding. It is sometimes urged that this gap is intrinsic to the topic: intelligence is not a unitary thing for which there will be a unifying theory, but rather a "society" of subintelligences whose overall behavior cannot be reduced to useful characterizing and predictive principles.
MidSized Axiomatizations of Commonsense Problems: A Case Study in Egg Cracking
 Studia Logica
, 2000
"... We present an axiomatization of a problem in commonsense reasoning, characterizing the proper procedure for cracking an egg and transferring its contents to a bowl. The axiomatization is midsized, larger than toy problems such as the Yale Shooting Problem or the Suitcase Problem, but much smalle ..."
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Cited by 28 (1 self)
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We present an axiomatization of a problem in commonsense reasoning, characterizing the proper procedure for cracking an egg and transferring its contents to a bowl. The axiomatization is midsized, larger than toy problems such as the Yale Shooting Problem or the Suitcase Problem, but much smaller than the comprehensive axiomatizations associated with CYC and HPKB. This size of axiomatization permits the development of nontrivial, reusable core theories of commonsense reasoning, acts as a testbed for existing theories of commonsense reasoning, and encourages the discovery of new problems in commonsense reasoning.