English

A counterexample to sparse removal

Combinatorics 2013-12-12 v1

Abstract

The Tur\'{a}n number of a graph HH, denoted \mboxex(n,H)\mbox{ex}(n,H), is the maximum number of edges in an nn-vertex graph with no subgraph isomorphic to HH. Solymosi conjectured that if HH is any graph and \mboxex(n,H)=O(nα)\mbox{ex}(n,H) = O(n^{\alpha}) where α>1\alpha > 1, then any nn-vertex graph with the property that each edge lies in exactly one copy of HH has o(nα)o(n^{\alpha}) edges. This can be viewed as conjecturing a possible extension of the removal lemma to sparse graphs, and is well-known to be true when HH is a non-bipartite graph, in particular when HH is a triangle, due to Ruzsa and Szemer\'{e}di. Using Sidon sets we exhibit infinitely many bipartite graphs HH for which the conjecture is false.

Keywords

Cite

@article{arxiv.1312.2994,
  title  = {A counterexample to sparse removal},
  author = {Craig Timmons and Jacques Verstraete},
  journal= {arXiv preprint arXiv:1312.2994},
  year   = {2013}
}
R2 v1 2026-06-22T02:25:03.208Z