Ramsey lower bounds for bounded degree hypergraphs

Abstract

We prove that for all $k\ge 3$ and any integers $\hat{I}”,n$ with $n\ge 2^{\hat{I}}”,$ there exists a $k$-graph on $n$ vertices with maximum degree at most $\hat{I}”$ such that $r(H)\geq\tw_{k-1}(c_k Δ) \cdot n$ for some constant $c_k>0$, where $\tw_k$ denotes the tower function. This makes the first progress toward a problem proposed by Conlon, Fox, and Sudakov (2009), who asked whether $r(H)\geq\tw_{k}(c_k Δ) \cdot n$ holds. Our proof relies on a novel construction of a $k$-graph on a growing number of vertices $n$ while keeping the maximum degree bounded by a fixed $\hat{I}”$.

11 pages