English

Spanning trees of a claw-free graph whose reducible stems have few leaves

Combinatorics 2021-12-09 v1

Abstract

Let TT be a tree, a vertex of degree one is a leaf of TT and a vertex of degree at least three is a branch vertex of TT. For two distinct vertices u,vu,v of TT, let PT[u,v]P_T[u,v] denote the unique path in TT connecting uu and v.v. For a leaf xx of TT, let yxy_x denote the nearest branch vertex to xx. For every leaf xx of TT, we remove the path PT[x,yx)P_T [x, y_x) from TT, where PT[x,yx)P_T [x, y_x) denotes the path connecting xx to yxy_x in TT but not containing yxy_x. The resulting subtree of TT is called the {\it reducible stem } of TT. In this paper, we first use a new technique of Gould and Shull to state a new short proof for a result of Kano et al. on the spanning tree with a bounded number of leaves in a claw-free graph. After that, we use that proof to give a sharp sufficient condition for a claw-free graph having a spanning tree whose reducible stem has few leaves.

Keywords

Cite

@article{arxiv.2112.04102,
  title  = {Spanning trees of a claw-free graph whose reducible stems have few leaves},
  author = {Pham Hoang Ha},
  journal= {arXiv preprint arXiv:2112.04102},
  year   = {2021}
}

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16 pages