Metaconcepts of rooted tree balance

Fuente: arXiv
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Main Authors: Fischer, Mareike, Hamann, Tom Niklas, Wicke, Kristina
Format: Preprint
Published: 2025
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author Fischer, Mareike
Hamann, Tom Niklas
Wicke, Kristina
author_facet Fischer, Mareike
Hamann, Tom Niklas
Wicke, Kristina
contents Measures of tree balance play an important role in many different research areas such as mathematical phylogenetics or theoretical computer science. Typically, tree balance is quantified by a single number which is assigned to the tree by a balance or imbalance index, of which several exist in the literature. Most of these indices are based on structural aspects of tree shape, such as clade sizes or leaf depths. For instance, indices like the Sackin index, total cophenetic index, and $\widehat{s}$-shape statistic all quantify tree balance through clade sizes, albeit with different definitions and properties. In this paper, we formalize the idea that many tree (im)balance indices are functions of similar underlying tree shape characteristics by introducing metaconcepts of tree balance. A metaconcept is a function $Φ_f$ that depends on a function $f$ capturing some aspect of tree shape, such as balance values, clade sizes, or leaf depths. These metaconcepts encompass existing indices but also provide new means of measuring tree balance. The versatility and generality of metaconcepts allow for the systematic study of entire families of (im)balance indices, providing deeper insights that extend beyond index-by-index analysis.
format Preprint
id arxiv_https___arxiv_org_abs_2506_08614
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Metaconcepts of rooted tree balance
Fischer, Mareike
Hamann, Tom Niklas
Wicke, Kristina
Populations and Evolution
Combinatorics
Measures of tree balance play an important role in many different research areas such as mathematical phylogenetics or theoretical computer science. Typically, tree balance is quantified by a single number which is assigned to the tree by a balance or imbalance index, of which several exist in the literature. Most of these indices are based on structural aspects of tree shape, such as clade sizes or leaf depths. For instance, indices like the Sackin index, total cophenetic index, and $\widehat{s}$-shape statistic all quantify tree balance through clade sizes, albeit with different definitions and properties. In this paper, we formalize the idea that many tree (im)balance indices are functions of similar underlying tree shape characteristics by introducing metaconcepts of tree balance. A metaconcept is a function $Φ_f$ that depends on a function $f$ capturing some aspect of tree shape, such as balance values, clade sizes, or leaf depths. These metaconcepts encompass existing indices but also provide new means of measuring tree balance. The versatility and generality of metaconcepts allow for the systematic study of entire families of (im)balance indices, providing deeper insights that extend beyond index-by-index analysis.
title Metaconcepts of rooted tree balance
topic Populations and Evolution
Combinatorics
url https://arxiv.org/abs/2506.08614