,
Daniel Frishberg
,
Michail Sarantis
,
Prasad Tetali
Creative Commons Attribution 4.0 International license
We prove an Õ(n²) bound for the relaxation time and the log-Sobolev time (inverse log-Sobolev constant) of the classical triangulation flip chain on a convex (n+2)-gon, implying a mixing time of Õ(n²). The previous state of the art for the mixing time of this chain due to Eppstein and Frishberg [Eppstein and Frishberg, 2023] was Õ(n³), while the best known lower bound on the mixing time due to Molloy, Reed and Steiger [Molloy et al., 1997] is Ω(n^{3/2}). Our relaxation time bound makes significant progress towards Aldous' [Aldous, 2003] conjectured bound of Θ(n^{3/2}) for the relaxation time.
We improve upon the analysis of [Eppstein and Frishberg, 2023] by further developing the framework of transport flows introduced in the work [Xiaoyu Chen et al., 2025] of Chen et al. In this light, our results can be seen as a more efficient way of using combinatorial decompositions to obtain functional inequalities for Markov chains. We hope our ideas will find other applications in the future.
@InProceedings{alev_et_al:LIPIcs.ICALP.2026.12,
author = {Alev, Vedat Levi and Frishberg, Daniel and Sarantis, Michail and Tetali, Prasad},
title = {{Faster Triangulation Mixing via Transport Flows}},
booktitle = {53rd International Colloquium on Automata, Languages, and Programming (ICALP 2026)},
pages = {12:1--12:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-428-4},
ISSN = {1868-8969},
year = {2026},
volume = {374},
editor = {Bhattacharya, Sayan and Nanongkai, Danupon and Benedikt, Michael and Puppis, Gabriele},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2026.12},
URN = {urn:nbn:de:0030-drops-264011},
doi = {10.4230/LIPIcs.ICALP.2026.12},
annote = {Keywords: triangulations, mixing time, log-Sobolev inequality, spectral gap, Markov chain, random walk, MCMC, transport flow, multicommodity flow}
}