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Handling contingency in temporal constraint networks: from consistency to controllabilities
 Journal of Experimental and Theoretical Artificial Intelligence
, 1999
"... This paper has been accepted for publication by the Journal of Experimental and Theoretical Arti cial Intelligence (JETAI) published byTaylor & Francis Ltd. Anyway, it should be pointed out that this version slightly di ers from the nal published one. Copyright 1999 T&F Ltd. Personal use of ..."
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Cited by 74 (4 self)
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This paper has been accepted for publication by the Journal of Experimental and Theoretical Arti cial Intelligence (JETAI) published byTaylor & Francis Ltd. Anyway, it should be pointed out that this version slightly di ers from the nal published one. Copyright 1999 T&F Ltd. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from Taylor & Francis Ltd
Temporal Representation and Reasoning in Artificial Intelligence: Issues and Approaches
, 2002
"... this paper, we survey a wide range of research in temporal representation and reasoning, without committing ourselves to the point of view of any speci c application ..."
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Cited by 26 (1 self)
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this paper, we survey a wide range of research in temporal representation and reasoning, without committing ourselves to the point of view of any speci c application
Temporal Constraints: A Survey
, 1998
"... . Temporal Constraint Satisfaction is an information technology useful for representing and answering queries about the times of events and the temporal relations between them. Information is represented as a Constraint Satisfaction Problem (CSP) where variables denote event times and constraints re ..."
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Cited by 26 (1 self)
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. Temporal Constraint Satisfaction is an information technology useful for representing and answering queries about the times of events and the temporal relations between them. Information is represented as a Constraint Satisfaction Problem (CSP) where variables denote event times and constraints represent the possible temporal relations between them. The main tasks are two: (i) deciding consistency, and (ii) answering queries about scenarios that satisfy all constraints. This paper overviews results on several classes of Temporal CSPs: qualitative interval, qualitative point, metric point, and some of their combinations. Research has progressed along three lines: (i) identifying tractable subclasses, (ii) developing exact search algorithms, and (iii) developing polynomialtime approximation algorithms. Most available techniques are based on two principles: (i) enforcing local consistency (e.g. pathconsistency), and (ii) enhancing naive backtracking search. Keywords: Temporal Constra...
A Model for Reasoning About Bidimensional Temporal Relations
, 1998
"... This paper introduces the rectangle algebra as the power set of the set of the pairs of atomic relations which can hold between two rational intervals. It goes on proving that the question of the consistency of a rectangle network which constraints are preconvex is decidable by means of the pa ..."
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Cited by 9 (0 self)
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This paper introduces the rectangle algebra as the power set of the set of the pairs of atomic relations which can hold between two rational intervals. It goes on proving that the question of the consistency of a rectangle network which constraints are preconvex is decidable by means of the pathconsistency method in time polynomial in the length of the network. 1 Introduction Temporal and spatial dependencies between data constitute the reason for existence of several problems in computer science : geographical information systems, natural language understanding, specification and verification of programs and systems, temporal and spatial databases, temporal and spatial planification, etc. Those who tackled these problems proposed numerous models for reasoning about time and space, the objects they considered as well as the relations between these objects distinguishing one of these models from the others. As an illustrative example, the model of the intervals proposed by Al...
Refinements and Independence: A Simple Method for Identifying Tractable Disjunctive Constraints
 IN: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON PRINCIPLES AND PRACTICE OF CONSTRAINT PROGRAMMING (CP2000
, 2000
"... The constraint satisfaction problem provides a natural framework for expressing many combinatorial problems. Since the general problem is NPhard, an important question is how to restrict the problem to ensure tractability. The concept of independence has proven to be a useful method for constru ..."
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Cited by 2 (1 self)
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The constraint satisfaction problem provides a natural framework for expressing many combinatorial problems. Since the general problem is NPhard, an important question is how to restrict the problem to ensure tractability. The concept of independence has proven to be a useful method for constructing tractable constraint classes from existing classes. Since checking the independence property may be a difficult task, we provide a simple method for checking this property. Our method builds on a somewhat surprising connection between independence and refinements which is a recently established way of reducing one constraint satisfaction problem to another. Refinements have two interesting properties: (1) they preserve consistency; and (2) their correctness can be easily checked by a computerassisted analysis. We show that all previous independence results of the point algebra for totally ordered and partially ordered time can be derived using this method. We also employ t...
A Model for Reasoning about Generalized Intervals
 in: Sixth International Conference on Principles of Knowledge Representation and Reasoning  KR'98, Trento  Italy
, 1998
"... Extending previous notions of generalized intervals, this paper defines the generalized interval as a tuple of solutions of some consistent interval network. It studies the possible relations between such generalized intervals and introduces the notion of a generalized interval network. It proves th ..."
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Extending previous notions of generalized intervals, this paper defines the generalized interval as a tuple of solutions of some consistent interval network. It studies the possible relations between such generalized intervals and introduces the notion of a generalized interval network. It proves the tractability of the problem of the consistency of a generalized network which constraints are preconvex.
Disjunctions, Independence, Refinements
"... An important question in constraint satisfaction is how to restrict the problem to ensure tractability (since the general problem is NPhard). The use of ..."
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An important question in constraint satisfaction is how to restrict the problem to ensure tractability (since the general problem is NPhard). The use of
Disjunctions
"... An important question in constraint satisfaction is how to restrict the problem to ensure tractability (since the general problem is NPhard). The use of disjunctions has proven to be a useful method for constructing tractable constraint classes from existing classes; the wellknown `maxclosed &apo ..."
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An important question in constraint satisfaction is how to restrict the problem to ensure tractability (since the general problem is NPhard). The use of disjunctions has proven to be a useful method for constructing tractable constraint classes from existing classes; the wellknown `maxclosed ' and `ORDHorn ' constraints are examples of tractable classes that can be constructed this way. Three sucient conditions (the guaranteed satisfaction property, 1independence and 2independence) that each ensure the tractability of constraints combined by disjunctions have been proposed in the literature. We show that these conditions are both necessary and sucient for tractability in three dierent natural classes of disjunctive constraints. This suggests that deciding this kind of property is a very important task when dealing with disjunctive constraints. We provide a simple, automatic method for checking the 1independence propertythis method is applicable whenever the consistency of the constraints under consideration can be decided by pathconsistency. Our method builds on a connection between independence and renements (which is a way of reducing one constraint satisfaction problem to another.)
Proceedings of the TwentyThird International Joint Conference on Artificial Intelligence Efficient Approach to Solve the Minimal Labeling Problem of Temporal and Spatial Qualitative Constraints
"... The Interval Algebra (IA) and a subset of the Region Connection Calculus (RCC), namely RCC8, are the dominant Artificial Intelligence approaches for representing and reasoning about qualitative temporal and topological relations respectively. Such qualitative information can be formulated as a Qual ..."
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The Interval Algebra (IA) and a subset of the Region Connection Calculus (RCC), namely RCC8, are the dominant Artificial Intelligence approaches for representing and reasoning about qualitative temporal and topological relations respectively. Such qualitative information can be formulated as a Qualitative Constraint Network (QCN). In this paper, we focus on the minimal labeling problem (MLP) and we propose an algorithm to efficiently derive all the feasible base relations of a QCN. Our algorithm considers chordal QCNs and a new form of partial consistency which we define as ◆ Gconsistency. Further, the proposed algorithm uses tractable subclasses of relations having a specific patchwork property for which ⋄consistency implies the consistency of the input QCN. Experimentations with QCNs of IA and RCC8 show the importance and efficiency of this new approach. 1