English

Random graphs with few disjoint cycles

Combinatorics 2012-10-11 v1

Abstract

The classical Erd\H{o}s-P\'{o}sa theorem states that for each positive integer k there is an f(k) such that, in each graph G which does not have k+1 disjoint cycles, there is a blocker of size at most f(k); that is, a set B of at most f(k) vertices such that G-B has no cycles. We show that, amongst all such graphs on vertex set {1,..,n}, all but an exponentially small proportion have a blocker of size k. We also give further properties of a random graph sampled uniformly from this class; concerning uniqueness of the blocker, connectivity, chromatic number and clique number. A key step in the proof of the main theorem is to show that there must be a blocker as in the Erd\H{o}s-P\'{o}sa theorem with the extra `redundancy' property that B-v is still a blocker for all but at most k vertices v in B.

Keywords

Cite

@article{arxiv.1010.6278,
  title  = {Random graphs with few disjoint cycles},
  author = {Valentas Kurauskas and Colin McDiarmid},
  journal= {arXiv preprint arXiv:1010.6278},
  year   = {2012}
}
R2 v1 2026-06-21T16:36:14.810Z