English

Degree conditions for Ramsey goodness of paths

Combinatorics 2024-03-21 v1

Abstract

A classical result of Chv\'atal implies that if n(r1)(t1)+1n \geq (r-1)(t-1) +1, then any colouring of the edges of KnK_n in red and blue contains either a monochromatic red KrK_r or a monochromatic blue PtP_t. We study a natural generalization of his result, determining the exact minimum degree condition for a graph GG on n=(r1)(t1)+1n = (r - 1)(t - 1) + 1 vertices which guarantees that the same Ramsey property holds in GG. In particular, using a slight generalization of a result of Haxell, we show that δ(G)nt/2\delta(G) \geq n - \lceil t/2 \rceil suffices, and that this bound is best possible. We also use a classical result of Bollob\'as, Erd\H{o}s, and Straus to prove a tight minimum degree condition in the case r=3r = 3 for all n2t1n \geq 2t - 1.

Keywords

Cite

@article{arxiv.2403.13742,
  title  = {Degree conditions for Ramsey goodness of paths},
  author = {Lucas Aragão and João Pedro Marciano and Walner Mendonça},
  journal= {arXiv preprint arXiv:2403.13742},
  year   = {2024}
}

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16 pages