Hypergraphs with arbitrarily small codegree Turán density
Abstrakt
The codegree Turán density gamma(F) of a k-graph F is the smallest gamma in [0, 1) such that every k-graph H with delta_(k-1)(H) >= (gamma + o(1))|V(H)| contains a copy of F. In this work, we show that for every epsilon > 0, there is a k-uniform hypergraph F with 0 < gamma(F) < epsilon. The initial preprint of this work leads to significant subsequent research on accumulation points of variants of the Turán density.