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A tree is scattered if no subdivision of the complete binary tree is a subtree. Building on results of Halin, Polat and Sabidussi, we identify four types of subtrees of a scattered tree and a function of the tree into the integers at least…

Combinatorics · Mathematics 2016-10-03 Claude Laflamme , Maurice Pouzet , Norbert Sauer

A subtree of a tree is any induced subgraph that is again a tree (i.e., connected). The mean subtree order of a tree is the average number of vertices of its subtrees. This invariant was first analyzed in the 1980s by Jamison. An intriguing…

Combinatorics · Mathematics 2021-06-11 Stijn Cambie , Stephan Wagner , Hua Wang

The Calkin-Wilf tree is an infinite binary tree whose vertices are the positive rational numbers. Each number occurs in the tree exactly once and in the form $a/b$, where are $a$ and $b$ are relatively prime positive integers. For every…

Number Theory · Mathematics 2020-04-22 Melvyn B. Nathanson

Full binary trees naturally represent commutative non-associative products. There are many important examples of these products: finite-precision floating-point addition and NAND gates, among others. Balance in such a tree is highly…

Discrete Mathematics · Computer Science 2021-08-27 Laura Monroe

For any cardinal $\kappa \geq 2$, there is a unique complete real tree whose points all have valence $\kappa$. In this note, we show that, when $\kappa \geq 3$, it is necessary to assume completeness. More precisely, we show that there…

Metric Geometry · Mathematics 2025-11-06 Pénélope Azuelos

This paper considers the enumeration of ternary trees (i.e. rooted ordered trees in which each vertex has 0 or 3 children) avoiding a contiguous ternary tree pattern. We begin by finding recurrence relations for several simple tree…

Combinatorics · Mathematics 2011-12-30 Nathan Gabriel , Katherine Peske , Lara Pudwell , Samuel Tay

The boxicity of a graph G, denoted as box(G) is defined as the minimum integer t such that G is an intersection graph of axis-parallel t-dimensional boxes. A graph G is a k-leaf power if there exists a tree T such that the leaves of the…

Combinatorics · Mathematics 2009-02-23 L. Sunil Chandran , Mathew C. Francis , Rogers Mathew

A congruence of the weak order is simple if its quotientope is a simple polytope. We provide an alternative elementary proof of the characterization of the simple congruences in terms of forbidden up and down arcs. For this, we provide a…

Combinatorics · Mathematics 2026-05-07 Emily Barnard , Jean-Christophe Novelli , Vincent Pilaud

We establish an explicit lower bound for Kruskal's weak tree function at n=3, proving that tree(3) >= 844,424,930,131,960 = 3 * 2^48 - 8. This is achieved by constructing an explicit sequence of unlabeled rooted trees satisfying the…

Combinatorics · Mathematics 2026-01-28 Mark Giroux

A $k-$quasiperfect dominating set ($k\ge 1$) of a graph $G$ is a vertex subset $S$ such that every vertex not in $S$ is adjacent to at least one and at most k vertices in $S$. The cardinality of a minimum k-quasiperfect dominating set in…

Combinatorics · Mathematics 2015-06-01 José Cáceres , Carmen Hernando , Mercé Mora , Ignacio M. Pelayo , María Luz Puertas

We study the Steiner $k$-eccentricity on trees, which generalizes the previous one in the paper [X.~Li, G.~Yu, S.~Klav\v{z}ar, On the average Steiner 3-eccentricity of trees, arXiv:2005.10319, 2020]. To support the algorithm, we achieve…

Combinatorics · Mathematics 2020-08-19 Xingfu Li , Guihai Yu , Sandi Klavžar , Jie Hu , Bo Li

Trees fill many extremal roles in graph theory, being minimally connected and serving a critical role in the definition of $n$-good graphs. In this article, we consider the generalization of trees to the setting of $r$-uniform hypergraphs…

Combinatorics · Mathematics 2017-10-17 Mark Budden , Andrew Penland

The subtrees and BC-subtrees (subtrees where any two leaves are at even distance apart) have been extensively studied in recent years. Such structures, under special constraints on degrees, have applications in many fields. Through an…

Combinatorics · Mathematics 2021-10-08 Yu Yang , Xiao-xiao Li , Meng-yuan Jin , Long Li , Hua Wang , Xiao-Dong Zhang

We study the notion of sparseness for regular languages over finite trees and infinite words. A language of trees is called sparse if the relative number of $n$-node trees in the language tends to zero, and a language of infinite words is…

Formal Languages and Automata Theory · Computer Science 2025-07-08 Kord Eickmeyer , Georg Schindling

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

A tree $T$ on $2^n$ vertices is called set-sequential if the elements in $V(T)\cup E(T)$ can be labeled with distinct nonzero $(n+1)$-dimensional $01$-vectors such that the vector labeling each edge is the component-wise sum modulo $2$ of…

Combinatorics · Mathematics 2021-11-09 Emily Eckels , Ervin Gyori , Junsheng Liu , Sohaib Nasir

Let $m_t(\alpha)$ denote the $t$-metric Mahler measure of the algebraic number $\alpha$. Recent work of the first author established that the infimum in $m_t(\alpha)$ is attained by a single point $\bar\alpha = (\alpha_1,\ldots,\alpha_N)\in…

Number Theory · Mathematics 2025-04-02 Charles L. Samuels , Tanner J. Strunk

This work addresses the problem of computing measures of recognisable sets of infinite trees. An algorithm is provided to compute the probability measure of a tree language recognisable by a weak alternating automaton, or equivalently…

Formal Languages and Automata Theory · Computer Science 2025-12-22 Damian Niwiński , Marcin Przybyłko , Michał Skrzypczak

Imitating a recently introduced invariant of trees, we initiate the study of the inducibility of $d$-ary trees (rooted trees whose vertex outdegrees are bounded from above by $d\geq 2$) with a given number of leaves. We determine the exact…

Combinatorics · Mathematics 2018-02-13 Éva Czabarka , Audace A. V. Dossou-Olory , László A. Székely , Stephan Wagner

Ply number is a recently developed graph drawing metric inspired by studying road networks. Informally, for each vertex v, which is associated with a point in the plane, a disk is drawn centered on v with a radius that is alpha times the…

Computational Geometry · Computer Science 2018-08-13 Michael T. Goodrich , Timothy Johnson