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Finding a maximum weight triangle in n3-Δ time, with applications
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Source Annual ACM Symposium on Theory of Computing archive
Proceedings of the thirty-eighth annual ACM symposium on Theory of computing table of contents
Seattle, WA, USA
SESSION: Session 5B table of contents
Pages: 225 - 231  
Year of Publication: 2006
ISBN:1-59593-134-1
Authors
Virginia Vassilevska  Carnegie Mellon University, Pittsburgh, PA
Ryan Williams  Carnegie Mellon University, Pittsburgh, PA
Sponsors
SIGACT: ACM Special Interest Group on Algorithms and Computation Theory
ACM: Association for Computing Machinery
Publisher
ACM  New York, NY, USA
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Downloads (6 Weeks): 3,   Downloads (12 Months): 66,   Citation Count: 5
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ABSTRACT

We present the first truly sub-cubic algorithms for finding a maximum node-weighted triangle in directed and undirected graphs with arbitrary real weights. The first is an O(B • n3+ω/2) = O(B • n2.688) deterministic algorithm, where n is the number of nodes, ω is the matrix multiplication exponent, and B is the number of bits of precision. The second is a strongly polynomial randomized algorithm that runs in O(n3+ω/2 log n) expected worst-case time. To achieve this, we show how to efficiently sample a weighted triangle uniformly at random, out of just those triangles whose total weight falls in some prescribed interval (W1,W2) for arbitrary weights W1 and W2. Previous approaches to the problem resulted in time bounds with either an exponential dependence on B, or a runtime of the form Ω(n3/(log n)c). The algorithms are easily extended to finding a maximum node-weighted induced subgraph on 3k nodes in Õ(n(3+ω)k/2) = O(n2.688 k) time.We give applications to a variety of problems, including a stable matching problem between buyers and sellers in computational economics, and discuss the possibility of extending our approach to a truly sub-cubic algorithm for computing all-pairs shortest paths on directed graphs with arbitrary weights.


REFERENCES

Note: OCR errors may be found in this Reference List extracted from the full text article. ACM has opted to expose the complete List rather than only correct and linked references.

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T. M. Chan. All-Pairs Shortest Paths with Real Weights in O(n3/log n) Time. In Proc. WADS, Springer-Verlag LNCS 3608, 318--324, 2005.
 
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A. Itai and M. Rodeh. Finding a minimum circuit in a graph. SIAM J. Computing, 7(4): 413--423, 1978.
 
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V. Vassilevska, R. Williams, and R. Yuster. Finding the smallest H-subgraph in real weighted graphs and related problems. Manuscript, in preparation.
 
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R. Yuster. Private communication.
 
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G. Yuval. An Algorithm for Finding All Shortest Paths Using N2.81 Infinite-Precision Multiplications. Inf. Proc. Letters 4: 155--156, 1976.
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Collaborative Colleagues:
Virginia Vassilevska: colleagues
Ryan Williams: colleagues