Article ID Journal Published Year Pages File Type
4655263 Journal of Combinatorial Theory, Series A 2014 21 Pages PDF
Abstract

Let G be an r-uniform hypergraph. When is it possible to orient the edges of G in such a way that every p-set of vertices has some p-degree equal to 0? (The p-degrees generalise for sets of vertices what in-degree and out-degree are for single vertices in directed graphs.) Caro and Hansberg asked if the obvious Hall-type necessary condition is also sufficient.Our main aim is to show that this is true for r large (for given p), but false in general. Our counterexample is based on a new technique in sparse Ramsey theory that may be of independent interest.

Keywords
Related Topics
Physical Sciences and Engineering Mathematics Discrete Mathematics and Combinatorics
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