English

Cutoff on all Ramanujan graphs

Probability 2016-08-25 v5 Combinatorics

Abstract

We show that on every Ramanujan graph GG, the simple random walk exhibits cutoff: when GG has nn vertices and degree dd, the total-variation distance of the walk from the uniform distribution at time t=dd2logd1n+slognt=\frac{d}{d-2}\log_{d-1} n + s\sqrt{\log n} is asymptotically P(Z>cs)\mathbb{P}(Z > c\, s) where ZZ is a standard normal variable and c=c(d)c=c(d) is an explicit constant. Furthermore, for all 1p1 \leq p \leq \infty, dd-regular Ramanujan graphs minimize the asymptotic LpL^p-mixing time for SRW among all dd-regular graphs. Our proof also shows that, for every vertex xx in GG as above, its distance from no(n)n-o(n) of the vertices is asymptotically logd1n\log_{d-1} n.

Keywords

Cite

@article{arxiv.1507.04725,
  title  = {Cutoff on all Ramanujan graphs},
  author = {Eyal Lubetzky and Yuval Peres},
  journal= {arXiv preprint arXiv:1507.04725},
  year   = {2016}
}

Comments

27 pages, 7 figures; to appear in GAFA

R2 v1 2026-06-22T10:13:24.989Z