English

Badges and rainbow matchings

Combinatorics 2021-02-17 v2

Abstract

Drisko proved that 2n12n-1 matchings of size nn in a bipartite graph have a rainbow matching of size nn. For general graphs it is conjectured that 2n2n matchings suffice for this purpose (and that 2n12n-1 matchings suffice when nn is even). The known graphs showing sharpness of this conjecture for nn even are called badges. We improve the previously best known bound from 3n23n-2 to 3n33n-3, using a new line of proof that involves analysis of the appearance of badges. We also prove a "cooperative" generalization: for t>0t>0 and n3n \geq 3, any 3n4+t3n-4+t sets of edges, the union of every tt of which contains a matching of size nn, have a rainbow matching of size nn.

Keywords

Cite

@article{arxiv.2004.07590,
  title  = {Badges and rainbow matchings},
  author = {Ron Aharoni and Joseph Briggs and Jinha Kim and Minki Kim},
  journal= {arXiv preprint arXiv:2004.07590},
  year   = {2021}
}

Comments

Accepted for publication in Discrete Mathematics. 19 pages, 2 figures

R2 v1 2026-06-23T14:53:34.901Z