Matchability and k-maximal matchings

  • Authors:
  • Brian C. Dean;Sandra M. Hedetniemi;Stephen T. Hedetniemi;Jason Lewis;Alice A. McRae

  • Affiliations:
  • School of Computing, Clemson University, Clemson, SC 29634, USA;School of Computing, Clemson University, Clemson, SC 29634, USA;School of Computing, Clemson University, Clemson, SC 29634, USA;School of Computing, Clemson University, Clemson, SC 29634, USA;Department of Computer Science, Appalachian State University. Boone, NC 28608, USA

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2011

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Abstract

We present a collection of new structural, algorithmic, and complexity results for matching problems of two types. The first problem involves the computation of k-maximal matchings, where a matching is k-maximal if it admits no augmenting path with @?2k vertices. The second involves finding a maximal set of vertices that is matchable - comprising one side of the edges in some matching. Among our results, we prove that the minimum cardinality @b"2 of a 2-maximal matching is at most the minimum cardinality @m of a maximal matchable set, with equality attained for triangle-free graphs. We show that the parameters @b"2 and @m are NP-hard to compute in bipartite and chordal graphs, but can be computed in linear time on a tree. Finally, we also give a simple linear-time algorithm for finding a 3-maximal matching, a consequence of which is a simple linear-time 3/4-approximation algorithm for the maximum-cardinality matching problem in a general graph.