On the scaling of random Tamari intervals and Schnyder woods of random triangulations (with an asymptotic D-finite trick)
Published Web Location
https://doi.org/10.5070/C65265404
Abstract
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.
Mathematics Subject Classifications: 05A15, 05A16, 60F99
Keywords: Tamari lattice, interval, scaling limit, asymptotics, method of moments, algebraic functions, computer algebra, random triangulation, catalytic variables, discrete differential equation