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15
Efficient Identification of Web Communities
 In Sixth ACM SIGKDD International Conference on Knowledge Discovery and Data Mining
, 2000
"... We de ne a community on the web as a set of sites that have more links (in either direction) to members of the community than to nonmembers. Members of such a community can be eciently identi ed in a maximum ow / minimum cut framework, where the source is composed of known members, and the sink c ..."
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Cited by 235 (12 self)
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We de ne a community on the web as a set of sites that have more links (in either direction) to members of the community than to nonmembers. Members of such a community can be eciently identi ed in a maximum ow / minimum cut framework, where the source is composed of known members, and the sink consists of wellknown nonmembers. A focused crawler that crawls to a xed depth can approximate community membership by augmenting the graph induced by the crawl with links to a virtual sink node. The effectiveness of the approximation algorithm is demonstrated with several crawl results that identify hubs, authorities, web rings, and other link topologies that are useful but not easily categorized. Applications of our approach include focused crawlers and search engines, automatic population of portal categories, and improved ltering.
A Combinatorial, Strongly PolynomialTime Algorithm for Minimizing Submodular Functions
, 2000
"... algorithm for minimizing submodular functions, answering an open question posed in 1981 by GrStschel, Lovsz, and Schrijver. The algorithm employs a scaling scheme that uses a flow in the complete directed graph on the underlying set with each arc capacity equal to the scaled parameter. The resulting ..."
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Cited by 63 (6 self)
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algorithm for minimizing submodular functions, answering an open question posed in 1981 by GrStschel, Lovsz, and Schrijver. The algorithm employs a scaling scheme that uses a flow in the complete directed graph on the underlying set with each arc capacity equal to the scaled parameter. The resulting algorithm runs in time bounded by a polynomial in the size of the underlying set and the largest length of the function value. The paper also presents a strongly polynomialtime version that runs in time bounded by a polynomial in the size of the underlying set independent of the function value.
Combinatorial Algorithms for the Generalized Circulation Problem
 MATHEMATICS OF OPERATIONS RESEARCH
, 1989
"... We consider a generalization of the maximum flow problem in which the amounts of flow entering and leaving an arc are linearly related. More precisely, if x(e) units of flow enter an arc e, x(e)fl(e) units arrive at the other end. For instance, nodes of the graph can correspond to different curre ..."
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Cited by 26 (3 self)
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We consider a generalization of the maximum flow problem in which the amounts of flow entering and leaving an arc are linearly related. More precisely, if x(e) units of flow enter an arc e, x(e)fl(e) units arrive at the other end. For instance, nodes of the graph can correspond to different currencies, with the multipliers being the exchange rates. We require conservation of flow at every node except a given source node. The goal is to maximize the amount of flow excess at the source. This problem is a special case of linear programming, and therefore can be solved in polynomial time. In this paper we present the first polynomial time combinatorial algorithms for this problem. The algorithms are simple and intuitive.
NonStandard Approaches to Integer Programming
, 2000
"... In this survey we address three of the principle algebraic approaches to integer programming. After introducing... ..."
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Cited by 22 (4 self)
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In this survey we address three of the principle algebraic approaches to integer programming. After introducing...
AverageCase Complexity of ShortestPaths Problems in the VertexPotential Model
 IN RANDOMIZATION AND APPROXIMATION TECHNIQUES IN COMPUTER SCIENCE (J. ROLIM, ED.), LECTURE NOTES IN COMPUT. SCI. 1269
, 2000
"... We study the averagecase complexity of shortestpaths problems in the vertexpotential model. The vertexpotential model is a family of probability distributions on complete directed graphs with arbitrary real edge lengths but without negative cycles. We show that on a graph with n vertices and ..."
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Cited by 10 (1 self)
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We study the averagecase complexity of shortestpaths problems in the vertexpotential model. The vertexpotential model is a family of probability distributions on complete directed graphs with arbitrary real edge lengths but without negative cycles. We show that on a graph with n vertices and with respect to this model, the singlesource shortestpaths problem can be solved in O(n²) expected time, and the allpairs shortestpaths problem can be solved in O(n² log n) expected time.
On Suboptimal Alignments of Biological Sequences
 Proc. 4th Symp. on Combinatorial Pattern Matching
, 1993
"... . It is widely accepted that the optimal alignmentbetween a pair of proteins or nucleic acid sequences that minimizes the edit distance may not necessarily re#ect the correct biological alignment. Alignments of proteins based on their structures or of DNA sequences based on evolutionary changes ..."
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Cited by 10 (0 self)
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. It is widely accepted that the optimal alignmentbetween a pair of proteins or nucleic acid sequences that minimizes the edit distance may not necessarily re#ect the correct biological alignment. Alignments of proteins based on their structures or of DNA sequences based on evolutionary changes are often di#erent from alignments that minimize edit distance. However, in many cases #e.g. when the sequences are close#, the edit distance alignment is a good approximation to the biological one. Since, for most sequences, the true alignment is unknown, a method that either assesses the signi#cance of the optimal alignment, or that provides few #close" alternatives to the optimal one, is of great importance. A suboptimal alignment is an alignment whose score lies within the neighborhood of the optimal score. Enumeration of suboptimal alignments #Wa83, WaBy# is not very practical since there are many such alignments. Other approaches #Zuk, Vi, ViAr# that use only partial informat...
Constructing Disjoint Paths for Secure Communication
 In Proc. of 17th Intl. Conference on Distributed Computing (DISC '03), volume 2848 of Lecture Notes in Computer Science
, 2003
"... We propose a bandwidthe#cient algorithmic solution for perfectlysecure communication in the absence of secure infrastructure. ..."
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Cited by 8 (3 self)
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We propose a bandwidthe#cient algorithmic solution for perfectlysecure communication in the absence of secure infrastructure.
Maximum skewsymmetric flows and matchings
 MATHEMATICAL PROGRAMMING
, 2004
"... The maximum integer skewsymmetric flow problem (MSFP) generalizes both the maximum flow and maximum matching problems. It was introduced by Tutte [28] in terms of selfconjugate flows in antisymmetrical digraphs. He showed that for these objects there are natural analogs of classical theoretical r ..."
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Cited by 6 (0 self)
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The maximum integer skewsymmetric flow problem (MSFP) generalizes both the maximum flow and maximum matching problems. It was introduced by Tutte [28] in terms of selfconjugate flows in antisymmetrical digraphs. He showed that for these objects there are natural analogs of classical theoretical results on usual network flows, such as the flow decomposition, augmenting path, and maxflow mincut theorems. We give unified and shorter proofs for those theoretical results. We then extend to MSFP the shortest augmenting path method of Edmonds and Karp [7] and the blocking flow method of Dinits [4], obtaining algorithms with similar time bounds in general case. Moreover, in the cases of unit arc capacities and unit “node capacities ” the blocking skewsymmetric flow algorithm has time bounds similar to those established in [8, 21] for Dinits ’ algorithm. In particular, this implies an algorithm for finding a maximum matching in a nonbipartite graph in O ( √ nm) time, which matches the time bound for the algorithm of Micali and Vazirani [25]. Finally, extending a clique compression technique of Feder and Motwani [9] to particular skewsymmetric graphs, we speed up the implied maximum matching algorithm to run in O ( √ nm log(n 2 /m)/log n) time, improving the best known bound for dense nonbipartite graphs. Also other theoretical and algorithmic results on skewsymmetric flows and their applications are presented.
Capacity Scaling Algorithm for Scalable Mconvex Submodular Flow Problems
 OPTIM. METHODS SOFTW
, 2003
"... An Mconvex function is a nonlinear discrete function defined on integer points introduced by Murota in 1996, and the Mconvex submodular flow problem is one of the most general frameworks of efficiently solvable combinatorial optimization problems. It includes the minimum cost flow and the submodul ..."
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Cited by 3 (1 self)
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An Mconvex function is a nonlinear discrete function defined on integer points introduced by Murota in 1996, and the Mconvex submodular flow problem is one of the most general frameworks of efficiently solvable combinatorial optimization problems. It includes the minimum cost flow and the submodular flow problems as its special cases. In this paper, we first devise a successive shortest path algorithm for the Mconvex submodular flow problem. We then propose an efficient algorithm based on a capacity scaling framework for the scalable Mconvex submodular flow problem. Here (x) := f(#x) is also Mconvex for any positive integer #.
AllPairs ShortestPaths Computation in the Presence of Negative Cycles
, 2001
"... We present an algorithm that solves the allpairs shortestpaths problem on a directed graph with n vertices and m arcs in time O(nm + n² log n), where the arcs are assigned real, possibly negative costs. Our algorithm is new in the following respect. It computes the distance (v; w) between each pai ..."
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Cited by 3 (2 self)
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We present an algorithm that solves the allpairs shortestpaths problem on a directed graph with n vertices and m arcs in time O(nm + n² log n), where the arcs are assigned real, possibly negative costs. Our algorithm is new in the following respect. It computes the distance (v; w) between each pair µ(v, w) of vertices even in the presence of negative cycles, where µ(v, w) is defined as the inmum of the costs of all directed paths from v to w.