English

Dirac-type theorems in random hypergraphs

Combinatorics 2022-08-05 v3

Abstract

For positive integers d<kd<k and nn divisible by kk, let md(k,n)m_{d}(k,n) be the minimum dd-degree ensuring the existence of a perfect matching in a kk-uniform hypergraph. In the graph case (where k=2k=2), a classical theorem of Dirac says that m1(2,n)=n/2m_{1}(2,n)=\lceil n/2\rceil. However, in general, our understanding of the values of md(k,n)m_{d}(k,n) is still very limited, and it is an active topic of research to determine or approximate these values. In this paper we prove a "transference" theorem for Dirac-type results relative to random hypergraphs. Specifically, for any d<kd< k, any ε>0\varepsilon>0 and any "not too small" pp, we prove that a random kk-uniform hypergraph GG with nn vertices and edge probability pp typically has the property that every spanning subgraph of GG with minimum degree at least (1+ε)md(k,n)p(1+\varepsilon)m_{d}(k,n)p has a perfect matching. One interesting aspect of our proof is a "non-constructive" application of the absorbing method, which allows us to prove a bound in terms of md(k,n)m_{d}(k,n) without actually knowing its value.

Keywords

Cite

@article{arxiv.2006.04370,
  title  = {Dirac-type theorems in random hypergraphs},
  author = {Asaf Ferber and Matthew Kwan},
  journal= {arXiv preprint arXiv:2006.04370},
  year   = {2022}
}