dorsal/arxiv
View SchemaGeneralized Zykov's Theorem
| Authors | Rajat Adak, L. Sunil Chandran |
|---|---|
| Categories | |
| ArXiv ID | 2512.02958vv2 |
| URL | https://arxiv.org/abs/2512.02958 |
| License | http://creativecommons.org/licenses/by/4.0/ |
Abstract
For a simple graph $G$, let $n$ denote its number of vertices, and let $N(G,K_t)$ denote the number of copies of $K_t$ in $G$. Zykov's theorem (1949) asserts that for any $K_{r+1}$-free graph and $t \ge 2$, \[ N(G,K_t) \le {r \choose t}\left(\frac{n}{r}\right)^t \] We generalize Zykov's bound within a vertex-based localization framework. For each vertex $v \in V(G)$, let $c(v)$ denote the order of the largest clique containing $v$. In this paper, we show that \[ N(G,K_t) \le n^{t-1} \sum_{v \in V(G)} \frac{1}{c(v)^t} {c(v) \choose t} \] We further show that equality holds if and only if $G$ is a regular complete multipartite graph. \newline Note that if we impose the condition that, $G$ is $K_{r+1}$-free, then $c(v) \leq r$ for all $v \in V(G)$. Thus, plugging $c(v) = r$ for all $v \in V(G)$, we retrieve Zykov's bound.
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"abstract": "For a simple graph $G$, let $n$ denote its number of vertices, and let $N(G,K_t)$ denote the number of copies of $K_t$ in $G$. Zykov\u0027s theorem (1949) asserts that for any $K_{r+1}$-free graph and $t \\ge 2$, \\[ N(G,K_t) \\le {r \\choose t}\\left(\\frac{n}{r}\\right)^t \\] We generalize Zykov\u0027s bound within a vertex-based localization framework.\n For each vertex $v \\in V(G)$, let $c(v)$ denote the order of the largest clique containing $v$. In this paper, we show that \\[ N(G,K_t) \\le n^{t-1} \\sum_{v \\in V(G)} \\frac{1}{c(v)^t} {c(v) \\choose t} \\] We further show that equality holds if and only if $G$ is a regular complete multipartite graph. \\newline Note that if we impose the condition that, $G$ is $K_{r+1}$-free, then $c(v) \\leq r$ for all $v \\in V(G)$. Thus, plugging $c(v) = r$ for all $v \\in V(G)$, we retrieve Zykov\u0027s bound.",
"arxiv_id": "2512.02958",
"authors": [
"Rajat Adak",
"L. Sunil Chandran"
],
"categories": [
"math.CO"
],
"license": "http://creativecommons.org/licenses/by/4.0/",
"title": "Generalized Zykov\u0027s Theorem",
"url": "https://arxiv.org/abs/2512.02958",
"version": "v2"
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