Sampling Planar Tanglegrams and Pairs of Disjoint Triangulations
Publication Date
5-16-2023
Document Type
Article
Organizational Units
College of Natural Science and Mathematics, Mathematics
Keywords
Planar tanglegram, Disjoint triangulation, Fixed triangulation, Convex polygon, Uniform distribution
Abstract
A tanglegram consists of two rooted binary trees and a perfect matching between their leaves, and a planar tanglegram is one that admits a layout with no crossings. We show that the problem of generating planar tanglegrams uniformly at random reduces to the corresponding problem for irreducible planar tanglegram layouts, which are known to be in bijection with pairs of disjoint triangulations of a convex polygon. We extend the flip operation on a single triangulation to a flip operation on pairs of disjoint triangulations. Interestingly, the resulting flip graph is both connected and regular, and hence a random walk on this graph converges to the uniform distribution. We also show that the restriction of the flip graph to the pairs with a fixed triangulation in either coordinate is connected, and give diameter bounds that are near optimal. Our results furthermore yield new insight into the flip graph of triangulations of a convex n-gon with a geometric interpretation on the associahedron.
Copyright Date
5-16-2023
Copyright Statement / License for Reuse
All Rights Reserved.
Rights Holder
Elsevier Inc.
Provenance
Received from author
Language
English (eng)
Publication Statement
Copyright is held by Elsevier Inc. User is responsible for all copyright compliance.
Publication Title
Advances in Applied Mathematics
Volume
149
First Page
102550
ISSN
1090-2074
Recommended Citation
Black, A. E., Liu, K., McDonough, A., Nelson, G., Wigal, M. C., Yin, M., & Yoo, Y. (2023). Sampling planar tanglegrams and pairs of disjoint triangulations. Advances in Applied Mathematics, 149, 102550. https://doi.org/10.1016/j.aam.2023.102550