Year: 2026
Type: preprint
Abstract: For an integer $L\ge2$, let $a=\lfloor L/2\rfloor$. Let $H(n,L)$ be the join of $K_a$ and an independent set of order $n-a$, with one extra edge in the independent set when $L$ is odd. We prove that, for fixed integers $q\ge4$ and $L>q$, and for all sufficiently large $n$, the graph $H(n,L)$ maximizes the number of copies of $C_q$ among all $n$-vertex graphs of circumference at most $L$. This settles a conjecture of Zhu, Győri, He, Lv, Salia and Xiao~[Bull. Lond. Math. Soc. 55 (2023)]. For even $q\ge6$, we also prove the boundary case $L=q$. We further determine the corresponding maximum when a long path is forbidden.
Source: arXiv (Cornell University)
Authors: Zhao, Xiamiao, Wang, Yuanpei
Institutions: Tsinghua University, Shanghai University
Subfield: Discrete Mathematics and Combinatorics
Field: Mathematics
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7168296871
Cites:
Cited by:
Related to: