New bounds for Ramsey numbers $R(K_k-e,K_l-e)$
Combinatorics
2021-07-12 v1 Discrete Mathematics
Abstract
Let denote the Ramsey number for the graphs , and let be . We present algorithms which enumerate all circulant and block-circulant Ramsey graphs for different types of graphs, thereby obtaining several new lower bounds on Ramsey numbers including: , , , , , , . We also use a gluing strategy to derive a new upper bound on . With both strategies combined, we prove the value of two Ramsey numbers: and . We also show that the 64-vertex extremal Ramsey graph for is unique. Furthermore, our algorithms also allow to establish new lower bounds and exact values on Ramsey numbers involving wheel graphs and complete bipartite graphs, including: , , , and .
Keywords
Cite
@article{arxiv.2107.04460,
title = {New bounds for Ramsey numbers $R(K_k-e,K_l-e)$},
author = {Jan Goedgebeur and Steven Van Overberghe},
journal= {arXiv preprint arXiv:2107.04460},
year = {2021}
}
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17 pages