English

Random Tur\'an Problems for Graphs with a Vertex Complete to One Part

Combinatorics 2026-04-03 v1

Abstract

Given a graph FF, the random Tur\'an problem asks to determine the maximum number of edges in an FF-free subgraph of Gn,pG_{n,p}. Prior to this work, the only bipartite graphs FF with known tight bounds included certain classes of complete bipartite graphs and theta graphs. We greatly expand upon these examples by proving tight bounds for a number of bipartite graphs which have a vertex complete to one part. We also prove new general upper bounds for this problem which in many cases do significantly better than the only previous known general upper bound due to Jiang and Longbrake. Our proofs utilize dependent random choice together with the recent technique of balanced vertex supersaturation in conjunction with hypergraph containers.

Keywords

Cite

@article{arxiv.2604.02264,
  title  = {Random Tur\'an Problems for Graphs with a Vertex Complete to One Part},
  author = {Sean Longbrake and Sam Spiro},
  journal= {arXiv preprint arXiv:2604.02264},
  year   = {2026}
}

Comments

38 pages, 1 figure