English

Few $T$ copies in $H$-saturated graphs

Combinatorics 2018-10-16 v2

Abstract

A graph is FF-saturated if it is FF-free but the addition of any edge creates a copy of FF. In this paper we study the quantity sat(n,H,F)\mathrm{sat}(n, H, F) which denotes the minimum number of copies of HH that an FF-saturated graph on nn vertices may contain. This parameter is a natural saturation analogue of Alon and Shikhelman's generalized Tur\'an problem, and letting H=K2H = K_2 recovers the well-studied saturation function. We provide a first investigation into this general function focusing on the cases where the host graph is either KsK_s or CkC_k-saturated. Some representative interesting behavior is: (a) For any natural number mm, there are graphs HH and FF such that sat(n,H,F)=Θ(nm)\mathrm{sat}(n, H, F) = \Theta(n^m). (b) For many pairs kk and ll, we show sat(n,Cl,Ck)=0\mathrm{sat}(n, C_l, C_k) = 0. In particular, we prove that there exists a triangle-free CkC_k-saturated graph on nn vertices for any k>4k > 4 and large enough nn. (c) sat(n,K3,K4)=n2\mathrm{sat}(n, K_3, K_4) = n-2, sat(n,C4,K4)n22\mathrm{sat}(n, C_4, K_4) \sim \frac{n^2}{2}, and sat(n,C6,K5)n3\mathrm{sat}(n, C_6, K_5) \sim n^3. We discuss several intriguing problems which remain unsolved.

Keywords

Cite

@article{arxiv.1810.00939,
  title  = {Few $T$ copies in $H$-saturated graphs},
  author = {Jürgen Kritschgau and Abhishek Methuku and Michael Tait and Craig Timmons},
  journal= {arXiv preprint arXiv:1810.00939},
  year   = {2018}
}

Comments

28 pages

R2 v1 2026-06-23T04:24:59.670Z