Markov embedding of ranked unlabelled evolutionary trees and its applications

Fuente: arXiv
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Main Authors: Fallesen, Lasse Thorup, Pauli, Simon, James, Elisabeth Sommer, Andersen, Lars Nørvang, Hobolth, Asger
Format: Preprint
Published: 2026
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author Fallesen, Lasse Thorup
Pauli, Simon
James, Elisabeth Sommer
Andersen, Lars Nørvang
Hobolth, Asger
author_facet Fallesen, Lasse Thorup
Pauli, Simon
James, Elisabeth Sommer
Andersen, Lars Nørvang
Hobolth, Asger
contents Rooted bifurcating trees are mathematical objects used to model evolutionary relationships and arise naturally in both coalescent theory and phylogenetics. Recent numerical representations of tree topologies, known as F-matrices, allow for summarizing a sample of trees via Fréchet means and provide new measures of tree balance. However, the number of ranked unlabelled trees grows super-exponentially with the number of leaves. This makes computation intensive and current methods rely on mixed integer programming and simulation-based methods. Moreover, F-matrices are difficult to interpret, and their distribution is only described in terms of first- and second-order moments under neutral branching. In this paper, we introduce a Markov chain embedding of ranked and unlabelled trees that drastically decreases the size of the state space. Leveraging this embedding, we develop an algorithm that efficiently computes all Fréchet means and use discrete phase-type theory to obtain the joint distribution of tree balance indices. We also use discrete phase-type theory to generalize previous results regarding moments of F-matrices to arbitrary order for any time homogeneous and bifurcating coalescent model. Using this framework, we construct three tests for neutrality and demonstrate their improved power compared to previous methods on simulated data.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15889
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Markov embedding of ranked unlabelled evolutionary trees and its applications
Fallesen, Lasse Thorup
Pauli, Simon
James, Elisabeth Sommer
Andersen, Lars Nørvang
Hobolth, Asger
Computation
Rooted bifurcating trees are mathematical objects used to model evolutionary relationships and arise naturally in both coalescent theory and phylogenetics. Recent numerical representations of tree topologies, known as F-matrices, allow for summarizing a sample of trees via Fréchet means and provide new measures of tree balance. However, the number of ranked unlabelled trees grows super-exponentially with the number of leaves. This makes computation intensive and current methods rely on mixed integer programming and simulation-based methods. Moreover, F-matrices are difficult to interpret, and their distribution is only described in terms of first- and second-order moments under neutral branching. In this paper, we introduce a Markov chain embedding of ranked and unlabelled trees that drastically decreases the size of the state space. Leveraging this embedding, we develop an algorithm that efficiently computes all Fréchet means and use discrete phase-type theory to obtain the joint distribution of tree balance indices. We also use discrete phase-type theory to generalize previous results regarding moments of F-matrices to arbitrary order for any time homogeneous and bifurcating coalescent model. Using this framework, we construct three tests for neutrality and demonstrate their improved power compared to previous methods on simulated data.
title Markov embedding of ranked unlabelled evolutionary trees and its applications
topic Computation
url https://arxiv.org/abs/2604.15889