English

Some sharp lower bounds for the bipartite Tur\'{a}n number of theta graphs

Combinatorics 2024-08-28 v1

Abstract

We expand Conlon's random algebraic construction to show that for any odd number k3k \geq 3 exists a natural number ckc_k (the same as Conlon's) such that ex(na,n,θk,ck)=Ωk,a((n1+a)k+12k)\operatorname{ex}(n^a,n,\theta_{k,c_k}) = \Omega_{k,a}((n^{1 + a})^{\frac{k + 1}{2k}}), with a[k1k+1,1)a \in [\frac{k - 1}{k + 1}, 1). Where given a graph HH, we denote by ex(n,m,H)\operatorname{ex}(n,m,H) the maximum number of edges an HH-free bipartite graph can have when the cardinalities of its parts are nn and mm. Also, we denote with θk,l\theta_{k,l} the graph where two vertices are connected through ll disjoint paths of length kk.

Keywords

Cite

@article{arxiv.2405.02864,
  title  = {Some sharp lower bounds for the bipartite Tur\'{a}n number of theta graphs},
  author = {Stefanos Theodorakopoulos},
  journal= {arXiv preprint arXiv:2405.02864},
  year   = {2024}
}

Comments

arXiv admin note: text overlap with arXiv:1411.0856 by other authors