English

Hitting time for Hamilton cycles in pseudorandom graphs

Combinatorics 2026-03-06 v1

Abstract

Consider the random subgraph process on a base graph GG with nn vertices: we generate a sequence {Gt}t=0E(G)\{G_t\}_{t=0}^{|E(G)|} by taking a uniformly random ordering of the edges of GG and then adding these edges one by one to the empty graph G0G_0 on the same vertex set. We prove that there is a constant C>0C > 0 such that if GG is an (n,d,λ)(n,d,\lambda)-graph with d/λCd/\lambda \ge C, then with high probability, the hitting time for the appearance of a Hamilton cycle coincides with the hitting time for reaching minimum degree 22. This resolves questions posed by Alon--Krivelevich in 2019 and by Frieze--Krivelevich in 2002. As a consequence, we determine the sharp threshold for Hamilton cycles in (n,d,λ)(n,d,\lambda)-graphs with d/λCd/\lambda\ge C for all dd sufficiently large. Lastly, we extend our result to the minimum degree 2k2k versus kk edge-disjoint Hamilton cycles setting for kcmin{d,logn}k \leq c\cdot \min\{d,\log n\} where cc is a constant depending on CC. This advances on a question asked by Frieze.

Keywords

Cite

@article{arxiv.2603.05269,
  title  = {Hitting time for Hamilton cycles in pseudorandom graphs},
  author = {Yaobin Chen and Yu Chen and Seonghyuk Im and Yiting Wang},
  journal= {arXiv preprint arXiv:2603.05269},
  year   = {2026}
}
R2 v1 2026-07-01T11:05:03.807Z