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We study hierarchical segmentation in the framework of edge-weighted graphs. We define ultrametric watersheds as topological watersheds null on the minima. We prove that there exists a bijection between the set of ultrametric watersheds and…

Discrete Mathematics · Computer Science 2011-03-17 Laurent Najman

Phylogenetic networks are a generalization of phylogenetic trees that are used to represent reticulate evolution. Unrooted phylogenetic networks form a special class of such networks, which naturally generalize unrooted phylogenetic trees.…

Populations and Evolution · Quantitative Biology 2016-01-11 Katharina T. Huber , Vincent Moulton , Taoyang Wu

In this article we study the treewidth of the \emph{display graph}, an auxiliary graph structure obtained from the fusion of phylogenetic (i.e., evolutionary) trees at their leaves. Earlier work has shown that the treewidth of the display…

Discrete Mathematics · Computer Science 2017-04-03 Steven Kelk , Georgios Stamoulis , Taoyang Wu

Agreement forests continue to play a central role in the comparison of phylogenetic trees since their introduction more than 25 years ago. More specifically, they are used to characterise several distances that are based on tree…

Combinatorics · Mathematics 2025-09-23 Steven Kelk , Simone Linz , Charles Semple

We investigate the interrelations between labeled trees and ultrametric spaces generated by these trees. The labeled trees, which generate complete ultrametrics, totally bounded ultrametrics, and discrete ones, are characterized up to…

Combinatorics · Mathematics 2022-01-27 Oleksiy Dovgoshey , Mehmet Küçükaslan

Merge trees are a type of graph-based topological summary that tracks the evolution of connected components in the sublevel sets of scalar functions. They enjoy widespread applications in data analysis and scientific visualization. In this…

Computational Geometry · Computer Science 2022-02-03 Ellen Gasparovic , Elizabeth Munch , Steve Oudot , Katharine Turner , Bei Wang , Yusu Wang

There are several tools available to infer phylogenetic trees, which depict the evolutionary relationships among biological entities such as viral and bacterial strains in infectious outbreaks, or cancerous cells in tumor progression trees.…

Data Structures and Algorithms · Computer Science 2023-12-22 António Pedro Branco , Cátia Vaz , Alexandre P. Francisco

High dimensional, sparsely populated data spaces have been characterized in terms of ultrametric topology. This implies that there are natural, not necessarily unique, tree or hierarchy structures defined by the ultrametric topology. In…

Computation and Language · Computer Science 2007-05-23 Fionn Murtagh

Rooted phylogenetic networks are used to describe evolutionary histories that contain non-treelike evolutionary events such as hybridization and horizontal gene transfer. In some cases, such histories can be described by a phylogenetic…

Populations and Evolution · Quantitative Biology 2016-10-03 Laura Jetten , Leo van Iersel

Phylogenetic inference-the derivation of a hypothesis for the common evolutionary history of a group of species- is an active area of research at the intersection of biology, computer science, mathematics, and statistics. One assumes the…

Populations and Evolution · Quantitative Biology 2016-06-21 Ruth Davidson , Joseph Rusinko , Zoe Vernon , Jing Xi

Phylogenetic trees are often constructed by using a metric on the set of taxa that label the leaves of the tree. While there are a number of methods for constructing a tree using a given metric, such trees will only display the metric if it…

Populations and Evolution · Quantitative Biology 2019-08-26 Michael Hendriksen , Andrew Francis

The rapid advancement of large language models (LLMs) has enabled significant strides in various fields. This paper introduces a novel approach to evaluate the effectiveness of LLM embeddings in the context of inherent geometric properties.…

Computational Geometry · Computer Science 2025-12-29 Prakash Chourasia , Sarwan Ali , Murray Patterson

Metric embedding has become a common technique in the design of algorithms. Its applicability is often dependent on how high the embedding's distortion is. For example, embedding finite metric space into trees may require linear distortion…

Data Structures and Algorithms · Computer Science 2007-05-23 Yair Bartal , Manor Mendel

Phylogenetic networks extend phylogenetic trees to model non-vertical inheritance, by which a lineage inherits material from multiple parents. The computational complexity of estimating phylogenetic networks from genome-wide data with…

Populations and Evolution · Quantitative Biology 2022-06-28 Jingcheng Xu , Cécile Ané

The number of the non-shared edges of two phylogenies is a basic measure of the dissimilarity between the phylogenies. The non-shared edges are also the building block for approximating a more sophisticated metric called the nearest…

Data Structures and Algorithms · Computer Science 2007-05-23 Wing-Kai Hon , Ming-Yang Kao , Tak-Wah Lam , Wing-Kin Sung , Siu-Ming Yiu

An ultrametric topology formalizes the notion of hierarchical structure. An ultrametric embedding, referred to here as ultrametricity, is implied by a hierarchical embedding. Such hierarchical structure can be global in the data set, or…

Methodology · Statistics 2011-01-11 Fionn Murtagh

Associated to any finite metric space are a large number of objects and quantities which provide some degree of structural or geometric information about the space. In this paper we show that in the setting of subsets of weighted Hamming…

Functional Analysis · Mathematics 2024-09-19 Ian Doust , Anthony Weston

A network $N$ on a finite set $X$, $|X|\geq 2$, is a connected directed acyclic graph with leaf set $X$ in which every root in $N$ has outdegree at least 2 and no vertex in $N$ has indegree and outdegree equal to 1; $N$ is arboreal if the…

Combinatorics · Mathematics 2023-08-14 Katharina T. Huber , Vincent Moulton , Guillaume E. Scholz

Phylogenetic networks are used to represent the evolutionary history of species. They are versatile when compared to traditional phylogenetic trees, as they capture more complex evolutionary events such as hybridization and horizontal gene…

Combinatorics · Mathematics 2023-05-18 Shunsuke Maeda , Yusuke Kaneko , Hideaki Muramatsu , Yukihiro Murakami , Momoko Hayamizu

The tree-metric theorem provides a necessary and sufficient condition for a dissimilarity matrix to be a tree metric, and has served as the foundation for numerous distance-based reconstruction methods in phylogenetics. Our main result is…

Combinatorics · Mathematics 2007-05-23 Lior Pachter , David E Speyer