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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

An evolutionary tree is a rooted tree where each internal vertex has at least two children and where the leaves are labeled with distinct symbols representing species. Evolutionary trees are useful for modeling the evolutionary history of…

Computational Engineering, Finance, and Science · Computer Science 2007-05-23 Ming-Yang Kao

The size of the largest common subtree (maximum agreement subtree) of two independent uniform random binary trees on $n$ leaves is known to be between orders $n^{1/8}$ and $n^{1/2}$. By a construction based on recursive splitting and…

Probability · Mathematics 2022-01-11 David J. Aldous

Let $G$ be a graph (with multiple edges allowed) and let $T$ be a tree in $G$. We say that $T$ is $\textit{even}$ if every leaf of $T$ belongs to the same part of the bipartition of $T$, and that $T$ is $\textit{weakly even}$ if every leaf…

In this series, we introduce and investigate the concept of connectoids, which captures the connectivity structure of various discrete objects such as undirected graphs, directed graphs, bidirected graphs, hypergraphs and finitary matroids.…

Combinatorics · Mathematics 2026-05-21 Nathan Bowler , Florian Reich

In 2006, Bar\'at and Thomassen posed the following conjecture: for each tree $T$, there exists a natural number $k_T$ such that, if $G$ is a $k_T$-edge-connected graph and $|E(G)|$ is divisible by $|E(T)|$, then $G$ admits a decomposition…

Combinatorics · Mathematics 2015-09-23 Fabio Botler , Guilherme O. Mota , Marcio T. I. Oshiro , Yoshiko Wakabayashi

Consider a rooted tree $T$ with leaf-set $[n]$, and with all non-leaf vertices having out-degree $2$, at least. A rooted tree $\mathcal T$ with leaf-set $S\subset [n]$ is induced by $S$ in $T$ if $\mathcal T$ is the lowest common ancestor…

Probability · Mathematics 2021-08-12 Boris Pittel

Let $T$ be a distinguished subset of vertices in a graph $G$. A $T$-\emph{Steiner tree} is a subgraph of $G$ that is a tree and that spans $T$. Kriesell conjectured that $G$ contains $k$ pairwise edge-disjoint $T$-Steiner trees provided…

Combinatorics · Mathematics 2015-08-11 Matt DeVos , Jessica McDonald , Irene Pivotto

A fringe subtree of a rooted tree is a subtree induced by one of the vertices and all its descendants. We consider the problem of estimating the number of distinct fringe subtrees in two types of random trees: simply generated trees and…

Combinatorics · Mathematics 2021-05-11 Louisa Seelbach Benkner , Stephan Wagner

Let $T$ be a random tree taken uniformly at random from the family of labelled trees on $n$ vertices. In this note, we provide bounds for $c(n)$, the number of sub-trees of $T$ that hold asymptotically almost surely. With computer support…

Combinatorics · Mathematics 2018-08-16 Bogumil Kaminski , Pawel Pralat

We prove that if $T_1,\dots, T_n$ is a sequence of bounded degree trees so that $T_i$ has $i$ vertices, then $K_n$ has a decomposition into $T_1,\dots, T_n$. This shows that the tree packing conjecture of Gy\'arf\'as and Lehel from 1976…

Combinatorics · Mathematics 2019-03-14 Felix Joos , Jaehoon Kim , Daniela Kühn , Deryk Osthus

Luo, Tian and Wu (2022) conjectured that for any tree $T$ with bipartition $X$ and $Y$, every $k$-connected bipartite graph $G$ with minimum degree at least $k+t$, where $t=$max$\{|X|,|Y|\}$, contains a tree $T'\cong T$ such that $G-V(T')$…

Combinatorics · Mathematics 2024-01-23 Qing Yang , Yingzhi Tian

We show that the expected size of the maximum agreement subtree of two $n$-leaf trees, uniformly random among all trees with the shape, is $\Theta(\sqrt{n})$. To derive the lower bound, we prove a global structural result on a decomposition…

Combinatorics · Mathematics 2018-09-13 Pratik Misra , Seth Sullivant

The minimum linear arrangement problem on a network consists of finding the minimum sum of edge lengths that can be achieved when the vertices are arranged linearly. Although there are algorithms to solve this problem on trees in polynomial…

Data Analysis, Statistics and Probability · Physics 2017-12-14 Juan Luis Esteban , Ramon Ferrer-i-Cancho , Carlos Gómez-Rodríguez

A variant of the Erd\H{o}s-S\'os conjecture, posed by Havet, Reed, Stein and Wood, states that every graph with minimum degree at least $\lfloor 2k/3 \rfloor$ and maximum degree at least $k$ contains a copy of every tree with $k$ edges.…

Combinatorics · Mathematics 2025-12-19 Alexey Pokrovskiy , Leo Versteegen , Ella Williams

A conjecture by Bollob\'as from 1995 (which is a weakenning of the famous Tree Packing Conjecture by Gy\'arf\'as from 1976) states that any set of $k$ trees $T_n,T_{n-1},\dots,T_{n-k+1}$, such that $T_{n-i}$ has $n-i$ vertices, pack into…

Combinatorics · Mathematics 2015-11-11 Andrzej Żak

This paper investigates some properties of the number of subtrees of a tree with given degree sequence. These results are used to characterize trees with the given degree sequence that have the largest number of subtrees, which generalizes…

Combinatorics · Mathematics 2012-09-04 Xiu-Mei Zhang , Xiao-Dong Zhang , Daniel Gray , Hua Wang

In this paper, we lay the groundwork on the comparison of phylogenetic networks based on edge contractions and expansions as edit operations, as originally proposed by Robinson and Foulds to compare trees. We prove that these operations…

Data Structures and Algorithms · Computer Science 2025-02-21 Bertrand Marchand , Nadia Tahiri , Olivier Tremblay-Savard , Manuel Lafond

In this thesis we consider ordered graphs (that is, graphs with a fixed linear ordering on their vertices). We summarize and further investigations on the number of edges an ordered graph may have while avoiding a fixed forbidden ordered…

Discrete Mathematics · Computer Science 2009-07-16 Craig Weidert

Given an edge-weighted tree $T$ with $n$ leaves, sample the leaves uniformly at random without replacement and let $W_k$, $2 \le k \le n$, be the length of the subtree spanned by the first $k$ leaves. We consider the question, "Can $T$ be…

Combinatorics · Mathematics 2015-06-04 Steven N. Evans , Daniel Lanoue