Projections of the Aldous chain on binary trees: Intertwining and consistency

<p>Consider the Aldous Markov chain on the space of rooted binary trees with n labeled leaves in which at each transition a uniform random leaf is deleted and reattached to a uniform random edge. Now, fix 1 ≤ k &lt; n and project the leaf mass onto the subtree spanned by the first k leaves...

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Bibliographic Details
Main Authors: Forman, N, Pal, S, Rizzolo, D, Winkel, M
Format: Journal article
Language:English
Published: Wiley 2020
Description
Summary:<p>Consider the Aldous Markov chain on the space of rooted binary trees with n labeled leaves in which at each transition a uniform random leaf is deleted and reattached to a uniform random edge. Now, fix 1 ≤ k &lt; n and project the leaf mass onto the subtree spanned by the first k leaves. This yields a binary tree with edge weights that we call a “decorated k ‐tree with total mass n .” We introduce label swapping dynamics for the Aldous chain so that, when it runs in stationarity, the decorated k ‐trees evolve as Markov chains themselves, and are projectively consistent over k . The construction of projectively consistent chains is a crucial step in the construction of the Aldous diffusion on continuum trees by the present authors, which is the n →∞ continuum analog of the Aldous chain and will be taken up elsewhere.</p>