English

On Tur\'{a}n problems for Cartesian products of graphs

Combinatorics 2019-05-13 v2

Abstract

Let A,BA,B be disjoint sets of sizes nn and mm. Let Q{\mathcal Q} be a family of quadruples, having 22 elements from AA and 22 from BB, such that any subset SABS \subseteq A \cup B with S=7|S|=7, SA2|S \cap A| \geq 2 and SB2|S \cap B| \geq 2 contains one of the quadruples. We prove that the smallest size of Q{\mathcal Q} is (1/16+O(1/n)+O(1/m))n2m2(1/16 + O(1/n) + O(1/m)) n^2 m^2 as n,mn,m\to\infty. We also solve asymptotically a more general two-partite Tur\'{a}n problem for quadruples.

Keywords

Cite

@article{arxiv.1812.01581,
  title  = {On Tur\'{a}n problems for Cartesian products of graphs},
  author = {Alexander Sidorenko},
  journal= {arXiv preprint arXiv:1812.01581},
  year   = {2019}
}

Comments

Changes suggested by the referees have been made