Year: 2026
Type: preprint
Abstract: In this note we prove $\mathrm{forb}(n,\mathbf{1}_{r-2}\times C_4)=Θ(n^{r-1/2})$, thus providing a series of counterexamples of a 2005 conjecture of the first two authors. Here $\mathbf{1}_{r-2}\times C_4$ is the $r$-extension of the 4-cycle, that is the $r$-uniform hypergraph of four edges obtained by joining a set of $r-2$ vertices to each edge of $C_4$. $\mathrm{forb}(n,F)$ is the largest number of edges of a simple hypergraph $G$ on $n$ vertices without \emph{trace} (induced subhypergraph) $F$.
Source: arXiv (Cornell University)
Authors: Anstee, Richard P., Sali, Attila, Wu, Pei
Language: English
Subfield: Discrete Mathematics and Combinatorics
Field: Mathematics
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7202176263