## Abstract Let __r__~__k__~(__G__) be the __k__‐color Ramsey number of a graph __G__. It is shown that $r\_{k}(C\_{5})\le \sqrt{18^{k}\,k!}$ for __k__⩾2 and that __r__~__k__~(__C__~2__m__+ 1~)⩽(__c__^__k__^__k__!)^1/__m__^ if the Ramsey graphs of __r__~__k__~(__C__~2__m__+ 1~) are not far away fr
Multipartite Ramsey numbers for odd cycles
✍ Scribed by András Gyárfás; Gábor N. Sárközy; Richard H. Schelp
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 119 KB
- Volume
- 61
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
In this paper we study multipartite Ramsey numbers for odd cycles. We formulate the following conjecture: Let n≥5 be an arbitrary positive odd integer; then, in any two‐coloring of the edges of the complete 5‐partite graph K((n−1)/2, (n−1)/2, (n−1)/2, (n−1)/2, 1) there is a monochromatic C~n~, a cycle of length n. This roughly says that the Ramsey number for C~n~ (i.e. 2__n__−1 ) will not change (somewhat surprisingly) if four large “holes” are allowed. Note that this would be best possible as the statement is not true if we delete from K~2__n__−1~ the edges within a set of size (n+ 1)/2. We prove an approximate version of the above conjecture. © 2009 Wiley Periodicals, Inc. J Graph Theory 61:12‐21, 2009
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