Improved Sidorenko bound for hypergraph Turan densities

Abstract

For every fixed integer $r\ge 3$, we prove that the Turán density of every $r$-uniform hypergraph $F$ with $m\ge 1$ edges satisfies $\pi (F)\le 1-c_r{m}^{-(r-1)/r}$, where $c_r>0$ depends only on $r$. This improves Sidorenko's general bound, whose gap from $1$ is of order $m^{-1}$. Complete $r$-uniform hypergraphs show that the exponent $(r-1)/r$ is optimal. The proof combines a potential argument for partial embeddings with the Lovász Local Lemma.

arXiv commentLean formalization is available at https://palomar-registry.org/entry.html?id=PALOMAR-2026-10-13-000012&version=1