English

Degrees in oriented hypergraphs and sparse Ramsey theory

Combinatorics 2013-12-02 v2

Abstract

Let GG be an rr-uniform hypergraph. When is it possible to orient the edges of GG in such a way that every pp-set of vertices has some pp-degree equal to 00? (The pp-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 rr large (for given pp), but false in general. Our counterexample is based on a new technique in sparse Ramsey theory that may be of independent interest.

Cite

@article{arxiv.1311.7082,
  title  = {Degrees in oriented hypergraphs and sparse Ramsey theory},
  author = {Vytautas Gruslys},
  journal= {arXiv preprint arXiv:1311.7082},
  year   = {2013}
}

Comments

20 pages, 3 figures

R2 v1 2026-06-22T02:16:15.683Z