List colorings of multipartite hypergraphs |
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Authors: | Ars Mroueh Andrew Thomason |
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Institution: | Arès Méroueh,Andrew Thomason |
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Abstract: | Let χl(G) denote the list chromatic number of the r‐uniform hypergraph G. Extending a result of Alon for graphs, Saxton and the second author used the method of containers to prove that, if G is simple and d‐regular, then . To see how close this inequality is to best possible, we examine χl(G) when G is a random r‐partite hypergraph with n vertices in each class. The value when r = 2 was determined by Alon and Krivelevich; here we show that almost surely, where d is the expected average degree of G and . The function g(r,α) is defined in terms of “preference orders” and can be determined fairly explicitly. This is enough to show that the container method gives an optimal lower bound on χl(G) for r = 2 and r = 3, but, perhaps surprisingly, apparently not for r ≥ 4. |
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Keywords: | hypergraph list colouring |
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