English

Note on a generalization of Gallai-Ramsey numbers

Combinatorics 2019-05-29 v1

Abstract

A colored complete graph is said to be Gallai-colored if it contains no rainbow triangle. This property has been shown to be equivalent to the existence of a partition of the vertices (of every induced subgraph) in which at most two colors appear on edges between the parts and at most one color appears on edges in between each pair of parts. We extend this notion by defining a coloring of a complete graph to be kk-Gallai if every induced subgraph has a nontrivial partition of the vertices such that there are at most kk colors present in between parts of the partition. The generalized (k,)(k, \ell) Gallai-Ramsey number of a graph HH is then defined to be the minimum number of vertices NN such that every kk-Gallai coloring of a complete graph KnK_{n} with nNn \geq N using at most \ell colors contains a monochromatic copy of HH. We prove bounds on these generalized (k,)(k, \ell) Gallai-Ramsey numbers based on the structure of HH, extending recent results for Gallai colorings.

Keywords

Cite

@article{arxiv.1905.11794,
  title  = {Note on a generalization of Gallai-Ramsey numbers},
  author = {Colton Magnant and Zhuojun Magnant},
  journal= {arXiv preprint arXiv:1905.11794},
  year   = {2019}
}