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In the study of extensions of polytopes of combinatorial optimization problems, a notorious open question is that for the size of the smallest extended formulation of the Minimum Spanning Tree problem on a complete graph with $n$ nodes. The…

离散数学 · 计算机科学 2017-01-03 Kaveh Khoshkhah , Dirk Oliver Theis

We define a new balance index for rooted phylogenetic trees based on the symmetry of the evolutive history of every set of 4 leaves. This index makes sense for multifurcating trees and it can be computed in time linear in the number of…

种群与进化 · 定量生物学 2019-03-25 Tomás M. Coronado , Arnau Mir , Francesc Rosselló , Gabriel Valiente

Binary jumbled pattern matching asks to preprocess a binary string $S$ in order to answer queries $(i,j)$ which ask for a substring of $S$ that is of length $i$ and has exactly $j$ 1-bits. This problem naturally generalizes to…

数据结构与算法 · 计算机科学 2014-07-01 Travis Gagie , Danny Hermelin , Gad M. Landau , Oren Weimann

In this paper and a companion paper, we prove that, if $m$ is sufficiently large, every graph on $m+1$ vertices that has a universal vertex and minimum degree at least $\lfloor \frac{2m}{3} \rfloor$ contains each tree $T$ with $m$ edges as…

组合数学 · 数学 2022-07-21 Bruce Reed , Maya Stein

A tree T_uni is m-universal for the class of trees if for every tree T of size m, T can be obtained from T_uni by successive contractions of edges. We prove that a m-universal tree for the class of trees has at least mln(m) + (gamma-1)m +…

离散数学 · 计算机科学 2009-11-17 Olivier Bodini

A phylogenetic tree shows the evolutionary relationships among species. Internal nodes of the tree represent speciation events and leaf nodes correspond to species. A goal of phylogenetics is to combine such trees into larger trees, called…

人工智能 · 计算机科学 2014-01-16 Neil C. A. Moore , Patrick Prosser

In this note, we obtain an upper bound on the maximum number of distinct non-empty palindromes in starlike trees. This bound implies, in particular, that there are at most $4n$ distinct non-empty palindromes in a starlike tree with three…

组合数学 · 数学 2018-05-29 Amy Glen , Jamie Simpson , W. F. Smyth

We consider the phylogenetic tree model in which every node of the tree is observed and binary and the transitions are given by the same matrix on each edge of the tree. We are able to compute the Grobner basis and Markov basis of the toric…

组合数学 · 数学 2007-05-23 Nicholas Eriksson

The {\sc Directed Maximum Leaf Out-Branching} problem is to find an out-branching (i.e. a rooted oriented spanning tree) in a given digraph with the maximum number of leaves. In this paper, we improve known parameterized algorithms and…

数据结构与算法 · 计算机科学 2007-07-10 Noga Alon , Fedor V. Fomin , Gregory Gutin , Michael Krivelevich , Saket Saurabh

We consider a continuous time random walk on the rooted binary tree of depth $n$ with all transition rates equal to one and study its cover time, namely the time until all vertices of the tree have been visited. We prove that, normalized by…

概率论 · 数学 2019-01-23 Aser Cortines , Oren Louidor , Santiago Saglietti

Let $P$ be a set of $n$ points in the plane in general position. We show that at least $\lfloor n/3\rfloor$ plane spanning trees can be packed into the complete geometric graph on $P$. This improves the previous best known lower bound…

计算几何 · 计算机科学 2019-02-26 Ahmad Biniaz , Alfredo García

In this paper we study binary trees with choosable edge lengths, in particular rooted binary trees with the property that the two edges leading from every non-leaf to its two children are assigned integral lengths $l_1$ and $l_2$ with…

信息论 · 计算机科学 2016-08-08 Jens Maßberg

We study spanners in planar domains, including polygonal domains, polyhedral terrain, and planar metrics. Previous work showed that for any constant $\epsilon\in (0,1)$, one could construct a $(2+\epsilon)$-spanner with $O(n\log(n))$ edges…

Phylogenetic networks are a generalisation of phylogenetic trees that allow for more complex evolutionary histories that include hybridisation-like processes. It is of considerable interest whether a network can be considered `tree-like' or…

种群与进化 · 定量生物学 2017-11-21 Michael Hendriksen

In this paper we study a family of algorithms, introduced by Chan [SODA 1999] and called LR-algorithms, for drawing ordered rooted binary trees. In particular, we are interested in constructing LR-drawings (that are drawings obtained via…

计算几何 · 计算机科学 2016-10-25 Fabrizio Frati , Maurizio Patrignani , Vincenzo Roselli

We prove limit theorems for sums of functions of subtrees of binary search trees and random recursive trees. In particular, we give simple new proofs of the fact that the number of fringe trees of size $ k=k_n $ in the binary search tree…

概率论 · 数学 2014-06-27 Cecilia Holmgren , Svante Janson

Let $\T_{n}$ be the set of rooted labeled trees on $\set{0,...,n}$. A maximal decreasing subtree of a rooted labeled tree is defined by the maximal subtree from the root with all edges being decreasing. In this paper, we study a new…

组合数学 · 数学 2022-03-22 Seunghyun Seo , Heesung Shin

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…

计算工程、金融与科学 · 计算机科学 2007-05-23 Ming-Yang Kao

Binary rooted trees, both in the ordered and in the un-ordered case, are well studied structures in the field of combinatorics. The aim of this work is to study particular patterns in these classes of trees. We consider completely…

组合数学 · 数学 2013-03-12 Filippo Disanto

We show that there exists a graph $G$ with $O(n)$ nodes, where any forest of $n$ nodes is a node-induced subgraph of $G$. Furthermore, for constant arboricity $k$, the result implies the existence of a graph with $O(n^k)$ nodes that…

数据结构与算法 · 计算机科学 2016-02-17 Stephen Alstrup , Søren Dahlgaard , Mathias Bæk Tejs Knudsen