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40
Fast Similarity Search in the Presence of Noise, Scaling, and Translation in TimeSeries Databases
 In VLDB
, 1995
"... We introduce a new model of similarity of time sequences that captures the intuitive notion that two sequences should be considered similar if they have enough nonoverlapping timeordered pairs of subsequences thar are similar. The model allows the amplitude of one of the two sequences to be scaled ..."
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Cited by 198 (6 self)
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We introduce a new model of similarity of time sequences that captures the intuitive notion that two sequences should be considered similar if they have enough nonoverlapping timeordered pairs of subsequences thar are similar. The model allows the amplitude of one of the two sequences to be scaled by any suitable amount and its offset adjusted appropriately. Two subsequences are considered similar if one can be enclosed within an envelope of a specified width drawn around the other. The model also allows nonmatching gaps in the matching subsequences. The matching subsequences need not be aligned along the time axis. Given this model of similarity,we present fast search techniques for discovering all similar sequences in a set of sequences. These techniques can also be used to find all (sub)sequences similar to a given sequence. We applied this matching system to the U.S. mutual funds data and discovered interesting matches.
Trust management for the semantic web
 In ISWC
, 2003
"... Abstract. Though research on the Semantic Web has progressed at a steady pace, its promise has yet to be realized. One major difficulty is that, by its very nature, the Semantic Web is a large, uncensored system to which anyone may contribute. This raises the question of how much credence to give ea ..."
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Cited by 193 (3 self)
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Abstract. Though research on the Semantic Web has progressed at a steady pace, its promise has yet to be realized. One major difficulty is that, by its very nature, the Semantic Web is a large, uncensored system to which anyone may contribute. This raises the question of how much credence to give each source. We cannot expect each user to know the trustworthiness of each source, nor would we want to assign topdown or global credibility values due to the subjective nature of trust. We tackle this problem by employing a web of trust, in which each user provides personal trust values for a small number of other users. We compose these trusts to compute the trust a user should place in any other user in the network. A user is not assigned a single trust rank. Instead, different users may have different trust values for the same user. We define properties for combination functions which merge such trusts, and define a class of functions for which merging may be done locally while maintaining these properties. We give examples of specific functions and apply them to data from Epinions and our BibServ bibliography server. Experiments confirm that the methods are robust to noise, and do not put unreasonable expectations on users. We hope that these methods will help move the Semantic Web closer to fulfilling its promise. 1.
QoS Routing Mechanisms and OSPF Extensions
 In Proceedings of the 2nd IEEE Global Internet MiniConference
, 1997
"... Status of this Memo ..."
Informationflow and dataflow analysis of whileprograms
 ACM Transactions on Programming Languages and Systems
, 1985
"... Until recently, informationflow analysis has been used primarily to verify that information transmission between program variables cannot violate security requirements. Here, the notion of information flow is explored as an aid to program development and validation. Informationflow relations are ..."
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Cited by 71 (0 self)
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Until recently, informationflow analysis has been used primarily to verify that information transmission between program variables cannot violate security requirements. Here, the notion of information flow is explored as an aid to program development and validation. Informationflow relations are presented for whileprograms, which identify those program statements whose execution may cause information to be transmitted from or to particular input, internal, or output values. It is shown with examples how these flow relations can be helpful in writing, testing, and updating programs; they also usefully extend the class of errors which can be detected automatically in the “static analysis ” of a program.
Algebra and Algorithms for QoS Path Computation and HopbyHop Routing in the Internet
 IEEE/ACM Transactions on Networking
, 2001
"... Prompted by the advent of QoS routing in the Internet, we investigate the properties that path weight functions must have so that hopbyhop routing is possible and optimal paths can be computed with a generalized Dijsktra's algorithm. For this purpose we define an algebra of weights which contains ..."
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Cited by 71 (2 self)
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Prompted by the advent of QoS routing in the Internet, we investigate the properties that path weight functions must have so that hopbyhop routing is possible and optimal paths can be computed with a generalized Dijsktra's algorithm. For this purpose we define an algebra of weights which contains a binary operation, for the composition of link weights into path weights, and an order relation. Isotonicity is the key property of the algebra. It states that the order relation between the weights of any two paths is preserved if both of them are either prefixed or appended by a common, third, path. We show that isotonicity is both necessary and sufficient for a generalized Dijkstra's algorithm to yield optimal paths. Likewise, isotonicity is also both necessary and sufficient for hopbyhop routing. However, without strict isotonicity, hopbyhop routing based on optimal paths may produce routing loops. They are prevented if every node computes what we call lexicographicoptimal paths. These paths can be computed with an enhanced Dijkstra's algorithm that has the same complexity as the standard one. Our findings are extended to multipath routing as well. As special cases of the general approach, we conclude that shortestwidest paths can neither be computed with a generalized Dijkstra's algorithm nor can packets be routed hopbyhop over those paths. In addition, loopfree hopbyhop routing over widest and widestshortest paths requires that each node computes lexicographicoptimal paths, in general.
Online Weighted Matching
, 1993
"... We introduce and study online versions of weighted matching problems in metric spaces. We present a simple 2k \Gamma 1 competitive algorithm for online minimum weighted bipartite matching where 2k is the number of nodes. We show that this competitiveness is optimal. For online maximum matching, we p ..."
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Cited by 49 (4 self)
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We introduce and study online versions of weighted matching problems in metric spaces. We present a simple 2k \Gamma 1 competitive algorithm for online minimum weighted bipartite matching where 2k is the number of nodes. We show that this competitiveness is optimal. For online maximum matching, we prove that the greedy algorithm achieves an optimal competitive factor of 3. In contrast, we prove that the greedy algorithm performs exponentially poorly for online minimum matching. Key words. online algorithm, matching, weighted matching, competitiveness AMS(MOS) subject classifications. 68P05, 68Q25, 68R10, 68R05 1 Introduction The assignment problem, finding a bipartite matching of minimum weight, is one of the archetypical problems in algorithmic graph theory and in combinatorial optimization [2, 10]. We introduce a natural online version of this problem, which we call online minmatching. Let G be a complete bipartite graph with one bipartition designated as the server vertices, an...
Duality and separation theorems in idempotent semimodules
 Linear Algebra and its Applications 379 (2004), 395–422. Also arXiv:math.FA/0212294
"... Abstract. We consider subsemimodules and convex subsets of semimodules over semirings with an idempotent addition. We introduce a nonlinear projection on subsemimodules: the projection of a point is the maximal approximation from below of the point in the subsemimodule. We use this projection to sep ..."
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Cited by 35 (19 self)
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Abstract. We consider subsemimodules and convex subsets of semimodules over semirings with an idempotent addition. We introduce a nonlinear projection on subsemimodules: the projection of a point is the maximal approximation from below of the point in the subsemimodule. We use this projection to separate a point from a convex set. We also show that the projection minimizes the analogue of Hilbert’s projective metric. We develop more generally a theory of dual pairs for idempotent semimodules. We obtain as a corollary duality results between the row and column spaces of matrices with entries in idempotent semirings. We illustrate the results by showing polyhedra and halfspaces over the maxplus semiring. 1.
Path Problems in Graphs
 COMPUTING SUPPL
, 1989
"... A large variety of problems in computer science can be viewed from a common viewpoint as instances of "algebraic" path problems. Among them are of course path problems in graphs such as the shortest path problem or problems of finding optimal paths with respect to more generally defined objective ..."
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Cited by 27 (0 self)
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A large variety of problems in computer science can be viewed from a common viewpoint as instances of "algebraic" path problems. Among them are of course path problems in graphs such as the shortest path problem or problems of finding optimal paths with respect to more generally defined objective functions; but also graph problems whose formulations do not directly involve the concept of a path, such as finding all bridges and articulation points of a graph; Moreover, there are even problems which seemingly have nothing to do with graphs, such as the solution of systems of linear equations, partial differentiation, or the determination of the regular expression describing the language accepted by a finite automaton. We describe the relation among these problems and their common algebraic foundation. We survey algorithms for solving them: vertex elimination algorithms such as GaußJordan elimination; and iterative algorithms such as the "classical" Jacobi and GaußSeidel iteration.
Exact and Approximate Reasoning about Qualitative Temporal Relations
, 1990
"... Much temporal information is qualitative information such as ‘‘The Cuban Missile crisis took place during Kennedy’s presidency,’ ’ where only the ordering of the end points of the two events is specified. A point and an interval algebra have been proposed for representing qualitative temporal inform ..."
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Cited by 24 (1 self)
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Much temporal information is qualitative information such as ‘‘The Cuban Missile crisis took place during Kennedy’s presidency,’ ’ where only the ordering of the end points of the two events is specified. A point and an interval algebra have been proposed for representing qualitative temporal information about the relationships between pairs of intervals and pairs of points, respectively. In this thesis, we address two fundamental reasoning tasks that arise in these algebras: Given (possibly indefinite) knowledge of the relationships between some intervals or points, • find a scenario that is consistent with the information provided, and • find the feasible relationships between some or all pairs of intervals or points. Solutions to these tasks have applications in natural language processing, planning, plan recognition, diagnosis, and knowledgebased systems. For the task of finding consistent scenarios the main results are as follows. For the point algebra, we develop an O(n 2) time algorithm that is an O(n) improvement over the previously known algorithm, where n is the number of points. For the interval algebra,
Idempotent Interval Analysis and Optimization Problems
 RELIABLE COMPUTING
, 2001
"... Many problems in optimization theory are strongly nonlinear in the traditional sense but possess a hidden linear structure over suitable idempotent semirings. After an overview of ‘Idempotent Mathematics ’ with an emphasis on matrix theory, interval analysis over idempotent semirings is developed. ..."
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Cited by 12 (1 self)
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Many problems in optimization theory are strongly nonlinear in the traditional sense but possess a hidden linear structure over suitable idempotent semirings. After an overview of ‘Idempotent Mathematics ’ with an emphasis on matrix theory, interval analysis over idempotent semirings is developed. The theory is applied to construction of exact interval solutions to the interval discrete stationary Bellman equation. Solution of an interval system is typically NPhard in the traditional interval linear algebra; in the idempotent case it is polynomial. A generalization to the case of positive semirings is outlined.