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We consider the numerical taxonomy problem of fitting a positive distance function ${D:{S\choose 2}\rightarrow \mathbb R_{>0}}$ by a tree metric. We want a tree $T$ with positive edge weights and including $S$ among the vertices so that…

Data Structures and Algorithms · Computer Science 2022-03-14 Vincent Cohen-Addad , Debarati Das , Evangelos Kipouridis , Nikos Parotsidis , Mikkel Thorup

The mutational heterogeneity of tumours can be described with a tree representing the evolutionary history of the tumour. With noisy sequencing data there may be uncertainty in the inferred tree structure, while we may also wish to study…

Computational Complexity · Computer Science 2025-01-14 Luís Cunha , Jack Kuipers , Thiago Lopes

Edit distance between trees is a natural generalization of the classical edit distance between strings, in which the allowed elementary operations are contraction, uncontraction and relabeling of an edge. Demaine et al. [ACM Trans. on…

Data Structures and Algorithms · Computer Science 2018-04-27 Bartłomiej Dudek , Paweł Gawrychowski

Given a graph $G$ and two spanning trees $T$ and $T'$ in $G$, Spanning Tree Reconfiguration asks whether there is a step-by-step transformation from $T$ to $T'$ such that all intermediates are also spanning trees of $G$, by exchanging an…

Combinatorics · Mathematics 2024-09-13 Tesshu Hanaka , Yuni Iwamasa , Yasuaki Kobayashi , Yuto Okada , Rin Saito

Let T be a weighted tree with n leaves. Let D_{i,j} be the distance between the leaves i and j. Let D_{i,j,k}= (D_{i,j} + D_{j,k} +D_{i,k})/2. We will call such numbers "triple weights" of the tree. In this paper, we give a…

Algebraic Geometry · Mathematics 2011-04-25 Elena Rubei

For a set $P$ of $n$ points in the plane in general position, a non-crossing spanning tree is a spanning tree of the points where every edge is a straight-line segment between a pair of points and no two edges intersect except at a common…

Kondo et al. (DS 2014) proposed methods for computing distances between unordered rooted trees by transforming an instance of the distance computing problem into an instance of the integer programming problem. They showed that the tree edit…

Data Structures and Algorithms · Computer Science 2017-06-13 Eunpyeong Hong , Yasuaki Kobayashi , Akihiro Yamamoto

We investigate the complexity of finding a transformation from a given spanning tree in a graph to another given spanning tree in the same graph via a sequence of edge flips. The exchange property of the matroid bases immediately yields…

Data Structures and Algorithms · Computer Science 2022-01-13 Nicolas Bousquet , Takehiro Ito , Yusuke Kobayashi , Haruka Mizuta , Paul Ouvrard , Akira Suzuki , Kunihiro Wasa

A fundamental problem in network science is the normalization of the topological or physical distance between vertices, that requires understanding the range of variation of the unnormalized distances. Here we investigate the limits of the…

Discrete Mathematics · Computer Science 2021-02-18 Ramon Ferrer-i-Cancho , Carlos Gómez-Rodríguez , Juan Luis Esteban

For a set $P$ of $n$ points in general position in the plane, the flip graph $F(P)$ has a vertex for each non-crossing spanning tree on $P$ and an edge between any two spanning trees that can be transformed into each other by one edge flip.…

Computational Geometry · Computer Science 2024-11-01 Håvard Bakke Bjerkevik , Linda Kleist , Torsten Ueckerdt , Birgit Vogtenhuber

We study the broadcast problem on dynamic networks with $n$ processes. The processes communicate in synchronous rounds along an arbitrary rooted tree. The sequence of trees is given by an adversary whose goal is to maximize the number of…

Distributed, Parallel, and Cluster Computing · Computer Science 2023-01-31 Antoine El-Hayek , Monika Henzinger , Stefan Schmid

The rank (also known as protection number or leaf-height) of a vertex in a rooted tree is the minimum distance between the vertex and any of its leaf descendants. We consider the sum of ranks over all vertices (known as the security) in…

Let $\Omega_n$ be the family of binary trees on $n$ vertices obtained by identifying the root of an rgood binary tree with a vertex of maximum eccentricity of a binary caterpillar. In the paper titled "On different middle parts of a tree…

Combinatorics · Mathematics 2020-09-28 Dinesh Pandey , Kamal Lochan Patra

The associahedron $\mathcal{A}(G)$ of a graph $G$ has the property that its vertices can be thought of as the search trees on $G$ and its edges as the rotations between two search trees. If $G$ is a simple path, then $\mathcal{A}(G)$ is the…

Combinatorics · Mathematics 2023-11-28 Jean Cardinal , Lionel Pournin , Mario Valencia-Pabon

We consider distance labeling schemes for trees: given a tree with $n$ nodes, label the nodes with binary strings such that, given the labels of any two nodes, one can determine, by looking only at the labels, the distance in the tree…

Data Structures and Algorithms · Computer Science 2015-07-16 Stephen Alstrup , Inge Li Gørtz , Esben Bistrup Halvorsen , Ely Porat

The rooted subtree prune and regraft (rSPR) distance between two rooted binary phylogenetic trees is a well-studied measure of topological dissimilarity that is NP-hard to compute. Here we describe an improved linear kernel for the problem.…

Data Structures and Algorithms · Computer Science 2023-08-21 Steven Kelk , Simone Linz , Ruben Meuwese

In this paper, we relate the seemingly unrelated concepts of treewidth and boxicity. Our main result is that, for any graph G, boxicity(G) <= treewidth(G) + 2. We also show that this upper bound is (almost) tight. Our result leads to…

Combinatorics · Mathematics 2007-05-23 L. Sunil Chandran , Naveen Sivadasan

We describe a kernel of size 9k-8 for the NP-hard problem of computing the Tree Bisection and Reconnect (TBR) distance k between two unrooted binary phylogenetic trees. We achieve this by extending the existing portfolio of reduction rules…

Data Structures and Algorithms · Computer Science 2022-09-21 Steven Kelk , Simone Linz , Ruben Meuwese

The edit distance between two rooted ordered trees with $n$ nodes labeled from an alphabet~$\Sigma$ is the minimum cost of transforming one tree into the other by a sequence of elementary operations consisting of deleting and relabeling…

Data Structures and Algorithms · Computer Science 2017-03-28 Karl Bringmann , Paweł Gawrychowski , Shay Mozes , Oren Weimann

In this paper, we show that the treewidth of the $n \times n$ toroidal grid is $2n-1$ for all $n \ge 5$. This closes the gap between the previously known upper bound of $2n-1$ (Ellis and Warren, DAM 2008) and the lower bound of $2n-2$…

Combinatorics · Mathematics 2026-05-21 Tatsuya Gima , Hiraku Morimoto , Yuto Okada , Yota Otachi