On the scaling of random Tamari intervals and Schnyder woods of random triangulations (with an asymptotic D-finite trick)

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Main Author: Chapuy, Guillaume
Format: Preprint
Published: 2024
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author Chapuy, Guillaume
author_facet Chapuy, Guillaume
contents We consider a Tamari interval of size $n$ (i.e., a pair of Dyck paths which are comparable for the Tamari relation) chosen uniformly at random. We show that the height of a uniformly chosen vertex on the upper or lower path scales as $n^{3/4}$, and has an explicit limit law. By the Bernardi-Bonichon bijection, this result also describes the height of points in the canonical Schnyder trees of a uniform random plane triangulation of size $n$. The exact solution of the model is based on polynomial equations with one and two catalytic variables. To prove the convergence from the exact solution, we use a version of moment pumping based on D-finiteness, which is essentially automatic and should apply to many other models. We are not sure to have seen this simple trick used before. It would be interesting to study the universality of this convergence for decomposition trees associated to positive Bousquet-Mélou--Jehanne equations.
format Preprint
id arxiv_https___arxiv_org_abs_2403_18719
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the scaling of random Tamari intervals and Schnyder woods of random triangulations (with an asymptotic D-finite trick)
Chapuy, Guillaume
Combinatorics
Symbolic Computation
Probability
We consider a Tamari interval of size $n$ (i.e., a pair of Dyck paths which are comparable for the Tamari relation) chosen uniformly at random. We show that the height of a uniformly chosen vertex on the upper or lower path scales as $n^{3/4}$, and has an explicit limit law. By the Bernardi-Bonichon bijection, this result also describes the height of points in the canonical Schnyder trees of a uniform random plane triangulation of size $n$. The exact solution of the model is based on polynomial equations with one and two catalytic variables. To prove the convergence from the exact solution, we use a version of moment pumping based on D-finiteness, which is essentially automatic and should apply to many other models. We are not sure to have seen this simple trick used before. It would be interesting to study the universality of this convergence for decomposition trees associated to positive Bousquet-Mélou--Jehanne equations.
title On the scaling of random Tamari intervals and Schnyder woods of random triangulations (with an asymptotic D-finite trick)
topic Combinatorics
Symbolic Computation
Probability
url https://arxiv.org/abs/2403.18719