English

Explicit cutoff profiles for colored top-$m$-to-random shuffles

Probability 2026-05-28 v2 Combinatorics

Abstract

We study pp-colored top-mm-to-random on the wreath product Gn,p=CpSnG_{n,p}=C_p\wr S_n, with mm fixed. Using the Nakano-Sadahiro-Sakurai basis elements BmB_m, we obtain exact nested-set occupancy mixtures and reduce the likelihood ratio to the single statistic LpL_p. This yields exact formulas for separation and L(U)L^\infty(U), and exact one-dimensional formulas for total variation, Lq(U)L^q(U) (1q<1\le q<\infty), χ2\chi^2, and relative entropy. At k=nm(logn+c)k=\Bigl\lfloor \frac{n}{m}(\log n+c)\Bigr\rfloor, the number of never-chosen labels in the associated mm-subset occupancy model converges in law to Poisson(ec)\mathrm{Poisson}(e^{-c}), giving the total-variation profile fp(c)f_p(c), the separation profile, and the corresponding Lq(U)L^q(U), L(U)L^\infty(U), χ2\chi^2, and relative-entropy profiles. For m=1m=1 we recover colored top-to-random; for p=1p=1, the total-variation profile reduces to the Diaconis-Fill-Pitman profile. For the reversed chain, we also identify optimal strong stationary times whose tail probabilities are exactly the separation distances.

Cite

@article{arxiv.2604.09933,
  title  = {Explicit cutoff profiles for colored top-$m$-to-random shuffles},
  author = {Ivan Z. Feng},
  journal= {arXiv preprint arXiv:2604.09933},
  year   = {2026}
}

Comments

45 pages

R2 v1 2026-07-01T12:03:54.308Z