English

The Hamilton cycle space of random graphs

Combinatorics 2025-07-08 v2

Abstract

The cycle space of a graph GG, denoted C(G)C(G), is a vector space over F2{\mathbb F}_2, spanned by all incidence vectors of edge-sets of cycles of GG. If GG has nn vertices, then Cn(G)C_n(G) denotes the subspace of C(G)C(G), spanned by the incidence vectors of Hamilton cycles of GG. A classical result in the theory of random graphs asserts that for GG(n,p)G \sim \mathbb{G}(n,p), asymptotically almost surely the necessary condition δ(G)2\delta(G) \geq 2 is also sufficient to ensure Hamiltonicity. Resolving a problem of Christoph, Nenadov, and Petrova, we augment this result by proving that for GG(n,p)G \sim \mathbb{G}(n,p), with nn being odd, asymptotically almost surely the condition δ(G)3\delta(G) \geq 3 (observed to be necessary by Heinig) is also sufficient for ensuring Cn(G)=C(G)C_n(G) = C(G). That is, not only does GG typically have a Hamilton cycle, but its Hamilton cycles are typically rich enough to span its cycle space.

Keywords

Cite

@article{arxiv.2506.19731,
  title  = {The Hamilton cycle space of random graphs},
  author = {Dan Hefetz and Michael Krivelevich},
  journal= {arXiv preprint arXiv:2506.19731},
  year   = {2025}
}
R2 v1 2026-07-01T03:31:49.286Z