Efficient approximation algorithms for shortest cycles in undirected graphs

We describe a simple combinatorial approximation algorithm for finding a shortest (simple) cycle in an undirected graph. Given an adjacency-list representation of an undirected graph G with n vertices and unknown girth k, our algorithm returns with high probability a cycle of length at most 2 k for...

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Bibliographic Details
Published in:Information processing letters Vol. 109; no. 10; pp. 493 - 498
Main Authors: Lingas, Andrzej, Lundell, Eva-Marta
Format: Journal Article
Language:English
Published: Amsterdam Elsevier B.V 30.04.2009
Elsevier
Elsevier Sequoia S.A
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ISSN:0020-0190, 1872-6119
Online Access:Get full text
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Summary:We describe a simple combinatorial approximation algorithm for finding a shortest (simple) cycle in an undirected graph. Given an adjacency-list representation of an undirected graph G with n vertices and unknown girth k, our algorithm returns with high probability a cycle of length at most 2 k for even k and 2 k + 2 for odd k, in time O ( n 3 2 log n ) . Thus, in general, it yields a 2 2 3 approximation. For a weighted, undirected graph, with non-negative edge weights in the range { 1 , 2 , … , M } , we present a simple combinatorial 2-approximation algorithm for a minimum weight (simple) cycle that runs in time O ( n 2 log n ( log n + log M ) ) .
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ISSN:0020-0190
1872-6119
DOI:10.1016/j.ipl.2009.01.008