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arXiv · 2111.05420

Three early problems on size Ramsey numbers

David Conlon·Jacob Fox·Yuval Wigderson
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Abstract

The size Ramsey number of a graph $H$ is defined as the minimum number of edges in a graph $G$ such that there is a monochromatic copy of $H$ in every two-coloring of $E(G)$. The size Ramsey number was introduced by Erdős, Faudree, Rousseau, and Schelp in 1978 and they ended their foundational paper by asking whether one can determine up to a constant factor the size Ramsey numbers of three families of graphs: complete bipartite graphs, book graphs (obtained by adding many common neighbors to the vertices of a clique), and starburst graphs (obtained by adding many pendant edges to each vertex of a clique). In this paper, we completely resolve the latter two questions and make substantial progress on the first by determining the size Ramsey number of $K_{s,t}$ up to a constant factor for all $t = Ω(s\log s)$.

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David Conlon, Jacob Fox, Yuval Wigderson. 2023-02-08. Three early problems on size Ramsey numbers. https://arxiv.org/abs/2111.05420

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