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Labeling schemes seek to assign a short label to each node in a network, so that a function on two nodes can be computed by examining their labels alone. For the particular case of trees, optimal bounds (up to low order terms) were recently…

Data Structures and Algorithms · Computer Science 2017-05-16 Ofer Freedman , Paweł Gawrychowski , Patrick K. Nicholson , Oren Weimann

We study properties of eigenvalues of a matrix associated with a randomly chosen partial automorphism of a regular rooted tree. We show that asymptotically, as the numbers of levels goes to infinity, the fraction of non-zero eigenvalues…

Group Theory · Mathematics 2020-06-30 Eugenia Kochubinska

We give a short and direct proof of a remarkable identity that arises in the enumeration of labeled trees with respect to their indegree sequence, where all edges are oriented from the vertex with lower label towards the vertex with higher…

Combinatorics · Mathematics 2016-01-20 Stephan Wagner

We study the asymptotic number of certain monotonically labeled increasing trees arising from a generalized evolution process. The main difference between the presented model and the classical model of binary increasing trees is that the…

Combinatorics · Mathematics 2019-10-30 Olivier Bodini , Antoine Genitrini , Bernhard Gittenberger , Stephan Wagner

Given a rooted tree $T$ with vertices $u_1,u_2,\ldots,u_n$, the level matrix $L(T)$ of $T$ is the $n \times n$ matrix for which the $(i,j)$-th entry is the absolute difference of the distances from the root to $v_i$ and $v_j$. This matrix…

Combinatorics · Mathematics 2023-09-21 Audace A. V. Dossou-Olory

We investigate the structure of trees that have greatest maximum eigenvalue among all trees with a given degree sequence. We show that in such an extremal tree the degree sequence is non-increasing with respect to an ordering of the…

Combinatorics · Mathematics 2008-04-18 Tuerker Biyikoglu , Marc Hellmuth , Josef Leydold

In the longest plane spanning tree problem, we are given a finite planar point set $\mathcal{P}$, and our task is to find a plane (i.e., noncrossing) spanning tree for $\mathcal{P}$ with maximum total Euclidean edge length. Despite more…

Computational Geometry · Computer Science 2024-05-02 Sergio Cabello , Michael Hoffmann , Katharina Klost , Wolfgang Mulzer , Josef Tkadlec

We investigate adjacency labeling schemes for graphs of bounded degree $\Delta = O(1)$. In particular, we present an optimal (up to an additive constant) $\log n + O(1)$ adjacency labeling scheme for bounded degree trees. The latter scheme…

Discrete Mathematics · Computer Science 2014-04-03 David Adjiashvili , Noy Rotbart

Let $T$ be a tree with a given adjacency eigenvalue $\lambda$. In this paper, by using the $\lambda$-minimal trees, we determine the structure of trees with a given multiplicity of the eigenvalue $\lambda$. Furthermore, we consider the…

Combinatorics · Mathematics 2021-01-05 Asghar Bahmani , Dariush Kiani

For a poset whose Hasse diagram is a rooted plane forest $F$, we consider the corresponding tree descent polynomial $A_F(q)$, which is a generating function of the number of descents of the labelings of $F$. When the forest is a path,…

Combinatorics · Mathematics 2019-09-02 Amy Grady , Svetlana Poznanović

We study the scaling limit of random forest with prescribed degree sequence in the regime that the largest tree consists of all but a vanishing fraction of nodes. We give a description of the limit of the forest consisting of the small…

Probability · Mathematics 2023-06-22 Tao Lei

There are several common ways to encode a tree as a matrix, such as the adjacency matrix, the Laplacian matrix (that is, the infinitesimal generator of the natural random walk), and the matrix of pairwise distances between leaves. Such…

Populations and Evolution · Quantitative Biology 2007-05-23 Frederick A. Matsen , Steven N. Evans

A vertex subset of a graph is called a distance-$k$ independent set if the distance between any two of its distinct vertices is at least $k + 1$. For all $n,k \geq 1$, we determine the minimum possible number of inclusion-wise maximal…

Combinatorics · Mathematics 2026-05-01 Dmitrii Taletskii

This extended abstract is dedicated to the analysis of the height of non-plane unlabelled rooted binary trees. The height of such a tree chosen uniformly among those of size $n$ is proved to have a limiting theta distribution, both in a…

Combinatorics · Mathematics 2008-07-16 Nicolas Broutin , Philippe Flajolet

For a graph $G$, let $\lambda_2(G)$ denote the second largest eigenvalue of the adjacency matrix of $G$. We determine the extremal trees with maximum/minimum adjacency eigenvalue $\lambda_2$ in the class $\mathcal{T}(n,d)$ of $n$-vertex…

Combinatorics · Mathematics 2024-09-04 Hitesh Kumar , Bojan Mohar , Shivaramakrishna Pragada , Hanmeng Zhan

We study that over some types of trees with a given number of vertices, which trees minimize or maximize the total number of subtrees. Trees minimizing (resp. maximizing) the total number of subtrees usually maximize (resp. minimize) the…

Combinatorics · Mathematics 2012-04-30 Shuchao Li , Shujing Wang

The goal of this expository note is to give a short, self-contained proof of nearly optimal lower bounds for the second largest eigenvalue of the adjacency matrix of regular graphs.

Combinatorics · Mathematics 2023-11-22 Igor Balla , Eero Räty , Benny Sudakov , István Tomon

We provide a logarithmic upper bound for the disentangling number on unordered lists of leaf labeled trees. This results is useful for analyzing phylogenetic mixture models. The proof depends on interpreting multisets of trees as high…

Combinatorics · Mathematics 2011-07-15 Seth Sullivant

We introduce weights on the unrooted unlabelled plane trees as follows: let $\mu$ be a probability measure on the set of nonnegative integers whose mean is no larger than $1$; then the $\mu$-weight of a plane tree $t$ is defined as $\Pi \,…

Probability · Mathematics 2016-08-02 Minmin Wang

This paper tightens the best known analysis of Hein's 1989 algorithm to infer the topology of a weighted tree based on the lengths of paths between its leaves. It shows that the number of length queries required for a degree-$k$ tree of $n$…

Data Structures and Algorithms · Computer Science 2024-12-05 Jack Gardiner , Lachlan L. H. Andrew , Junhao Gan , Jean Honorio , Seeun William Umboh