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Attempting to recognize a tree inside a phylogenetic network is a fundamental undertaking in evolutionary analysis. In the last few years, therefore, tree-based phylogenetic networks, which are defined by a spanning tree called a…

组合数学 · 数学 2020-09-29 Momoko Hayamizu

In analogy to a concept of Fibonacci trees, we define the leaf-Fibonacci tree of size $n$ and investigate its number of nonisomorphic leaf-induced subtrees. Denote by $f_0$ the one vertex tree and $f_1$ the tree that consists of a root with…

组合数学 · 数学 2018-11-16 Audace Amen Vioutou Dossou-Olory

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…

组合数学 · 数学 2015-06-04 Steven N. Evans , Daniel Lanoue

Let T d (n) be the set of d-ary rooted trees with n internal nodes. We give a method to construct a sequence (t n , n $\ge$ 0) where, for any n $\ge$ 1, t n has the uniform distribution in T d (n), and t n is constructed from t n--1 by the…

组合数学 · 数学 2021-05-13 Jean-Francois Marckert

We present here a new and universal approach for the study of random and/or trees, unifying in one framework many different models, including some novel ones not yet understood in the literature. An and/or tree is a Boolean expression…

概率论 · 数学 2017-06-09 Nicolas Broutin , Cécile Mailler

We propose new succinct representations of ordinal trees, which have been studied extensively. It is known that any $n$-node static tree can be represented in $2n + o(n)$ bits and a number of operations on the tree can be supported in…

数据结构与算法 · 计算机科学 2010-09-27 Gonzalo Navarro , Kunihiko Sadakane

In this paper, we provide algorithms to rank and unrank certain degree-restricted classes of Cayley trees (spanning trees of the n-vertex complete graph). Specifically, we consider classes of trees that have a given set of leaves or a fixed…

组合数学 · 数学 2010-09-13 Jeffrey B. Remmel , S. Gill Williamson

Chung and Graham [J. London Math. Soc. 1983] claimed to prove that there exists an $n$-vertex graph $G$ with $ \frac{5}{2}n \log_2 n + O(n)$ edges that contains every $n$-vertex tree as a subgraph. Frati, Hoffmann and T\'oth [Combin.…

组合数学 · 数学 2026-02-04 Neel Kaul , Jaehoon Kim , Minseo Kim , David R. Wood

We prove that every oriented tree on $n$ vertices with bounded maximum degree appears as a spanning subdigraph of every directed graph on $n$ vertices with minimum semidegree at least $n/2+o(n)$. This can be seen as a directed graph…

组合数学 · 数学 2026-05-20 Richard Mycroft , Tássio Naia

Phylogenetic networks are a generalization of phylogenetic trees that allow for representation of reticulate evolution. Recently, a space of unrooted phylogenetic networks was introduced, where such a network is a connected graph in which…

种群与进化 · 定量生物学 2017-03-09 Andrew Francis , Katharina Huber , Vincent Moulton , Taoyang Wu

We study the distribution of fringe trees in Patricia tries (extending earlier results by Ischebeck (2025)) and compressed binary search trees; both cases are random binary trees that have been compressed by deleting nodes of outdegree 1 so…

概率论 · 数学 2026-02-03 Svante Janson

We show that the class of finite rooted binary plane trees is a Ramsey class (with respect to topological embeddings that map leaves to leaves). That is, for all such trees P,H and every natural number k there exists a tree T such that for…

组合数学 · 数学 2010-05-26 Manuel Bodirsky , Diana Piguet

Motivated by the study of random temporal networks, we introduce a class of random trees that we coin \emph{uniform temporal trees}. A uniform temporal tree is obtained by assigning independent uniform $[0,1]$ labels to the edges of a…

概率论 · 数学 2025-01-23 Caelan Atamanchuk , Luc Devroye , Gabor Lugosi

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 $2n-2$…

组合数学 · 数学 2026-05-21 Tatsuya Gima , Hiraku Morimoto , Yuto Okada , Yota Otachi

There exist several methods dealing with the reconstruction of rooted phylogenetic networks explaining different evolutionary histories given by rooted binary phylogenetic trees. In practice, however, due to insufficient information of the…

种群与进化 · 定量生物学 2015-12-18 Benjamin Albrecht

Given an $n$-point metric space $(X,d_X)$, a tree cover $\mathcal{T}$ is a set of $|\mathcal{T}|=k$ trees on $X$ such that every pair of vertices in $X$ has a low-distortion path in one of the trees in $\mathcal{T}$. Tree covers have been…

数据结构与算法 · 计算机科学 2025-11-19 Yu Chen , Zihan Tan , Hangyu Xu

In evolutionary biology, phylogenetic trees are commonly inferred from a set of characters (partitions) of a collection of biological entities (e.g., species or individuals in a population). Such characters naturally arise from molecular…

种群与进化 · 定量生物学 2023-11-17 Katharina T. Huber , Simone Linz , Vincent Moulton , Charles Semple

Several indices that measure the degree of balance of a rooted phylogenetic tree have been proposed so far in the literature. In this work we define and study a new index of this kind, which we call the total cophenetic index: the sum, over…

种群与进化 · 定量生物学 2014-02-11 Arnau Mir , Francesc Rossello , Lucia Rotger

We investigate the number of permutations that occur in random labellings of trees. This is a generalisation of the number of subpermutations occurring in a random permutation. It also generalises some recent results on the number of…

概率论 · 数学 2022-12-22 Michael Albert , Cecilia Holmgren , Tony Johansson , Fiona Skerman

Measures of tree balance play an important role in different research areas such as mathematical phylogenetics or theoretical computer science. The balance of a tree is usually quantified in a single number, called a balance or imbalance…

组合数学 · 数学 2024-06-28 Bryan Currie , Kristina Wicke