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Induced subgraphs of graphs with large deficiency

Combinatorics 2025-05-22 v1

Abstract

The deficiency of a graph GG, denoted by \kd(G)\kd(G), is the number of vertices not saturated by a maximum matching. A bone BiB_i is the tree obtained by attaching two pendent edges to each of the end vertices of a path PiP_{i}. The local independence number of GG, denoted by αl(G)\alpha_l(G), is defines as the maximum integer tt such that GG contains an induced star K1,tK_{1,t}. Motivated by the seminal works of Scott and Seymour~(2016), Chudnovsky et al. (2017, 2020) on finding special types of holes in graphs with large chromatic number and bounded clique number, we establish an analog result by finding special types of bones in graphs with large deficiency and bounded local independence number. Fujita et al. (2006) proved that \kd(G)n2\kd(G)\le n-2 if GG is a connected graph with αl(G)<n\alpha_l(G)<n and containing no bones. We further establish exact extremal deficiency bounds for connected graphs with bounded local independence number that exclude specific bone configurations. An algorithm that constructs large matchings and establishes an upper bound on the deficiency is also provided.

Keywords

Cite

@article{arxiv.2505.15149,
  title  = {Induced subgraphs of graphs with large deficiency},
  author = {Jin Sun and Xinmin Hou},
  journal= {arXiv preprint arXiv:2505.15149},
  year   = {2025}
}

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26 pages