Graphs and Combinatorics ( IF 0.6 ) Pub Date : 2020-05-02 , DOI: 10.1007/s00373-020-02175-8 Xihe Li , Pierre Besse , Colton Magnant , Ligong Wang , Noah Watts
Given graphs G and H and a positive integer k, the Gallai–Ramsey number, denoted by \(gr_{k}(G : H)\) is defined to be the minimum integer n such that every coloring of \(K_{n}\) using at most k colors will contain either a rainbow copy of G or a monochromatic copy of H. We consider this question in the cases where \(G \in \{P_{4}, P_{5}\}\). In the case where \(G = P_{4}\), we completely solve the Gallai–Ramsey question by reducing to the 2-color Ramsey numbers. In the case where \(G = P_{5}\), we conjecture that the problem reduces to the 3-color Ramsey numbers and provide several results in support of this conjecture.
中文翻译:
Gallai–Ramsey彩虹路径编号
给定图G和H以及正整数k,用\(gr_ {k}(G:H)\)表示的Gallai–Ramsey数被定义为最小整数n,使得\(K_ {n } \)使用最多k种颜色将包含G的彩虹副本或H的单色副本。我们在\(G \ in \ {P_ {4},P_ {5} \} \)的情况下考虑这个问题。在\(G = P_ {4} \)的情况下,我们通过简化为2色Ramsey数来完全解决Gallai–Ramsey问题。在\(G = P_ {5} \)的情况下,我们猜想该问题将减少为3色Ramsey数,并提供若干结果支持该猜想。