Matroid Matching Via Mixed Skew-Symmetric Matrices

  • Authors:
  • James Geelen;Satoru Iwata

  • Affiliations:
  • Department of Combinatorics and Optimization, University of Waterloo, Waterloo, Canada;Department of Mathematical Informatics, University of Tokyo, Tokyo 1138656, Japan

  • Venue:
  • Combinatorica
  • Year:
  • 2005

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Abstract

Tutte associates a V by V skew-symmetric matrix T, having indeterminate entries, with a graph G=(V,E). This matrix, called the Tutte matrix, has rank exactly twice the size of a maximum cardinality matching of G. Thus, to find the size of a maximum matching it suffices to compute the rank of T. We consider the more general problem of computing the rank of T + K where K is a real V by V skew-symmetric matrix. This modest generalization of the matching problem contains the linear matroid matching problem and, more generally, the linear delta-matroid parity problem. We present a tight upper bound on the rank of T + K by decomposing T + K into a sum of matrices whose ranks are easy to compute.