PreprintCC0HAL
The Aldous chain on cladograms mixes in order n2 steps
Abstract
Cladograms of size n are unrooted binary trees whose leaves are labelled from 1 to n. Aldous introduced in 2000 a Markov chain on cladograms, a step of which consists of removing a leaf uniformly at random and reinserting it on a uniformly chosen edge. We introduce a coupling for this walk, which follows multiple colored subtrees in parallel. We go around the lack of independence of the colored components by finding a relevant statistic, namely the sum of the squares of the sizes of all colored components, which we prove has a drift. We deduce that the mixing time of the walk is of order n2, solving a conjecture of Aldous.
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BibTeX
@misc{feray2026aldous,
title = {{The Aldous chain on cladograms mixes in order $n^2$ steps}},
author = {Valentin Féray and Lucas Teyssier},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16955},
eprint = {2609.16955},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05772585v1},
note = {CC0},
}
RIS
TY - UNPB
TI - The Aldous chain on cladograms mixes in order n^2 steps
AU - Valentin Féray
AU - Lucas Teyssier
PY - 2026
DA - 2026/09/15
PB - HAL
DO - 10.48550/arxiv.2609.16955
UR - https://hal.science/hal-05772585v1
AB - Cladograms of size n are unrooted binary trees whose leaves are labelled from 1 to n. Aldous introduced in 2000 a Markov chain on cladograms, a step of which consists of removing a leaf uniformly at random and reinserting it on a uniformly chosen edge. We introduce a coupling for this walk, which follows multiple colored subtrees in parallel. We go around the lack of independence of the colored components by finding a relevant statistic, namely the sum of the squares of the sizes of all colored components, which we prove has a drift. We deduce that the mixing time of the walk is of order n^2, solving a conjecture of Aldous.
ER -