English

The maximum number of cliques in graphs without long cycles

Combinatorics 2017-09-13 v2

Abstract

The Erd\H{o}s--Gallai Theorem states that for k3k\geq 3 every graph on nn vertices with more than 12(k1)(n1)\frac{1}{2}(k-1)(n-1) edges contains a cycle of length at least kk. Kopylov proved a strengthening of this result for 2-connected graphs with extremal examples Hn,k,tH_{n,k,t} and Hn,k,2H_{n,k,2}. In this note, we generalize the result of Kopylov to bound the number of ss-cliques in a graph with circumference less than kk. Furthermore, we show that the same extremal examples that maximize the number of edges also maximize the number of cliques of any fixed size. Finally, we obtain the extremal number of ss-cliques in a graph with no path on kk-vertices.

Keywords

Cite

@article{arxiv.1701.07472,
  title  = {The maximum number of cliques in graphs without long cycles},
  author = {Ruth Luo},
  journal= {arXiv preprint arXiv:1701.07472},
  year   = {2017}
}