Theory of Computing Systems

, Volume 39, Issue 1, pp 3–14

Matching Algorithms Are Fast in Sparse Random Graphs

Authors

    • Max-Planck-Institut fur Informatik, Stuhlsatzenhausweg 85, 66123 Saarbrucken
    • Max-Planck-Institut fur Informatik, Stuhlsatzenhausweg 85, 66123 Saarbrucken
    • Max-Planck-Institut fur Informatik, Stuhlsatzenhausweg 85, 66123 Saarbrucken
    • Meiji University, School of Science and Technology, 1-1-1 HigashiMita, Tama, Kawasaki 214-8571
Article

DOI: 10.1007/s00224-005-1254-y

Cite this article as:
Bast, H., Mehlhorn, K., Schafer, G. et al. Theory Comput Syst (2006) 39: 3. doi:10.1007/s00224-005-1254-y

Abstract

We present an improved average case analysis of the maximum cardinality matching problem. We show that in a bipartite or general random graph on n vertices, with high probability every non-maximum matching has an augmenting path of length O(log n). This implies that augmenting path algorithms like the Hopcroft-Karp algorithm for bipartite graphs and the Micali-Vazirani algorithm for general graphs, which have a worst case running time of O(m√n), run in time O(m log n) with high probability, where m is the number of edges in the graph. Motwani proved these results for random graphs when the average degree is at least ln (n) [Average Case Analysis of Algorithms for Matchings and Related Problems, Journal of the ACM, 41(6):1329-1356, 1994]. Our results hold if only the average degree is a large enough constant. At the same time we simplify the analysis of Motwani.

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© Springer 2005