English

Generalized planar Tur\'an numbers related to short cycles

Combinatorics 2024-05-15 v1

Abstract

Given two graphs HH and FF, the generalized planar Tur\'an number exP(n,H,F)\mathrm{ex}_\mathcal{P}(n,H,F) is the maximum number of copies of HH that an nn-vertex FF-free planar graph can have. We investigate this function when HH and FF are short cycles. Namely, for large nn, we find the exact value of exP(n,Cl,C3)\mathrm{ex}_\mathcal{P}(n, C_l,C_3), where ClC_l is a cycle of length ll, for 4l64\leq l\leq 6, and determine the extremal graphs in each case. Also, considering the converse of these problems, we determine sharp upper bounds for exP(n,C3,Cl)\mathrm{ex}_\mathcal{P}(n,C_3,C_l), for 4l64\leq l\leq 6.

Keywords

Cite

@article{arxiv.2405.08162,
  title  = {Generalized planar Tur\'an numbers related to short cycles},
  author = {Ervin Győri and Hilal Hama Karim},
  journal= {arXiv preprint arXiv:2405.08162},
  year   = {2024}
}