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Efficient Algorithms for Qualitative Reasoning about Time
 Artificial Intelligence
, 1995
"... Reasoning about temporal information is an important task in many areas of Artificial Intelligence. In this paper we address the problem of scalability in temporal reasoning by providing a collection of new algorithms for efficiently managing large sets of qualitative temporal relations. We focus on ..."
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Cited by 32 (6 self)
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Reasoning about temporal information is an important task in many areas of Artificial Intelligence. In this paper we address the problem of scalability in temporal reasoning by providing a collection of new algorithms for efficiently managing large sets of qualitative temporal relations. We focus on the class of relations forming the Point Algebra (PArelations) and on a major extension to include binary disjunctions of PArelations (PAdisjunctions). Such disjunctions add a great deal of expressive power, including the ability to stipulate disjointness of temporal intervals, which is important in planning applications. Our representation of time is based on timegraphs, graphs partitioned into a set of chains on which the search is supported by a metagraph data structure. The approach is an extension of the time representation proposed by Schubert, Taugher and Miller in the context of story comprehension. The algorithms herein enable construction of a timegraph from a given set of PAr...
Java Subtype Tests in RealTime
 In Proceedings of the European Conference on Object Oriented Programming (ECOOP03
, 2003
"... Dynamic subtype tests are frequent operations in Java programs. ..."
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Cited by 16 (4 self)
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Dynamic subtype tests are frequent operations in Java programs.
On Computing the Minimal Labels in Time Point Algebra Networks
, 1995
"... We analyze the problem of computing the minimal labels for a network of temporal relations in the Point Algebra. van Beek proposes an algorithm for accomplishing this task which takes O(max(n 3 ; n 2 \Delta m)) time (for n points and m 6=relations). We show that the proof of the correctness of ..."
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Cited by 11 (6 self)
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We analyze the problem of computing the minimal labels for a network of temporal relations in the Point Algebra. van Beek proposes an algorithm for accomplishing this task which takes O(max(n 3 ; n 2 \Delta m)) time (for n points and m 6=relations). We show that the proof of the correctness of this algorithm given by van Beek and Cohen is faulty, and we provide a new proof showing that the algorithm is indeed correct. Keywords: temporal reasoning, Point Algebra, constraint networks, reasoning with inequations The work of the first author was carried out in part during a visit at the Computer Science Department of the University of Rochester (NY) supported by the Italian National Research Council (CNR), and in part at IRST in the context of the MAIA project and CNR projects "Sistemi Informatici e Calcolo Parallelo" and "Pianificazione Automatica". The second author was supported by Rome Lab Contract F3060291C0010. 1 Introduction The Interval Algebra (IA) (Allen 1983) and t...
On Pointbased Temporal Disjointness
 Artificial Intelligence
, 1994
"... We address the problems of determining consistency and of finding a solution for sets of 3point relations expressing exclusion of a point from an interval, and for sets of 4point relations expressing interval disjointness. Availability of these relations is an important requirement for dealing wit ..."
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Cited by 3 (0 self)
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We address the problems of determining consistency and of finding a solution for sets of 3point relations expressing exclusion of a point from an interval, and for sets of 4point relations expressing interval disjointness. Availability of these relations is an important requirement for dealing with the sorts of temporal constraints encountered in many AI applications such as plan reasoning. We prove that consistency testing is NPcomplete and finding a solution is NPhard. Keywords: temporal reasoning, complexity of reasoning, planning, reasoning with disjunctions The work of the first author was carried out in part during a visit at the Computer Science Department of the University of Rochester (NY) supported by the Italian National Research Council (CNR), and in part at IRST in the context of the MAIA project and CNR projects "Sistemi Informatici e Calcolo Parallelo" and "Pianificazione Automatica". The second author was supported by Rome Lab Contract F3060291C0010. 1 Introd...
The Temporal Reasoning Systems TimeGraph III
, 1994
"... We describe two domainindependent temporal reasoning systems called TimeGraph I and II which can be used in AIapplications as tools for efficiently managing large sets of relations in the Point Algebra, in the Interval Algebra, and metric information such as absolute times and durations. Our re ..."
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Cited by 2 (0 self)
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We describe two domainindependent temporal reasoning systems called TimeGraph I and II which can be used in AIapplications as tools for efficiently managing large sets of relations in the Point Algebra, in the Interval Algebra, and metric information such as absolute times and durations. Our representation of time is based on timegraphs, graphs partitioned into a set of chains on which the search is supported by a metagraph data structure. TimeGraph I was originally developed by Taugher, Schubert and Miller in the context of story comprehension. TimeGraph II provides useful extensions, including efficient algorithms for handing inequations, and relations expressing pointinterval exclusion and interval disjointness. These extensions make the system much more expressive in the representation of qualitative information and suitable for a large class of applications. Keywords: Temporal reasoning systems, Point algebra, Interval Algebra, Scalable systems 1 1 Introduction We ...
ACKNOWLEDGMENT Thank you Eva for keeping me alive THE GENEROUS FINANCIAL HELP OF THE TECHNION IS GRATEFULLY ACKNOWLEDGED Contents
"... List of Tables ix List of Algorithms xi Abstract 1 ..."