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Tree-decompositions and treewidth are of fundamental importance in structural and algorithmic graph theory. The "spread" of a tree-decomposition is the minimum integer $s$ such that every vertex lies in at most $s$ bags. A…

Combinatorics · Mathematics 2026-04-08 Marc Distel , Neel Kaul , Raj Kaul , David R. Wood

Tree-decompositions of graphs are of fundamental importance in structural and algorithmic graph theory. The main property of tree-decompositions is the width (the maximum size of a bag minus 1). We show that every graph has a…

Combinatorics · Mathematics 2026-05-08 David R. Wood

We study inferring a tree-structured representation from a single image for object shading. Prior work typically uses the parametric or measured representation to model shading, which is neither interpretable nor easily editable. We propose…

Computer Vision and Pattern Recognition · Computer Science 2023-09-14 Chen Geng , Hong-Xing Yu , Sharon Zhang , Maneesh Agrawala , Jiajun Wu

A graph is called pseudo-outerplanar if each block has an embedding on the plane in such a way that the vertices lie on a fixed circle and the edges lie inside the disk of this circle with each of them crossing at most one another. In this…

Combinatorics · Mathematics 2011-10-20 Xin Zhang , Guizhen Liu , Jian-Liang Wu

We prove that for $k \in \mathbb{N}$ and $d \leq 2k+2$, if a graph has maximum average degree at most $2k + \frac{2d}{d+k+1}$, then $G$ decomposes into $k+1$ pseudoforests, where one of the pseudoforests has all connected components having…

Combinatorics · Mathematics 2019-06-27 Logan Grout , Benjamin Moore

This paper studies graphs that have two tree decompositions with the property that every bag from the first decomposition has a bounded-size intersection with every bag from the second decomposition. We show that every graph in each of the…

Combinatorics · Mathematics 2018-05-21 Vida Dujmović , Gwenaël Joret , Pat Morin , Sergey Norin , David R. Wood

The Schr\"odinger operator on a metric tree is a family of ordinary differential operators on its edges complemented by certain matching conditions at the vertices. The regular trees are highly symmetric. This allows one to construct an…

Spectral Theory · Mathematics 2007-05-23 Michael Solomyak

Multi-edge trees as introduced in a recent paper of Dziemia\'nczuk are plane trees where multiple edges are allowed. We first show that $d$-ary multi-edge trees where the out-degrees are bounded by $d$ are in bijection with classical…

Combinatorics · Mathematics 2016-05-18 Clemens Heuberger , Helmut Prodinger , Stephan Wagner

This paper develops an algorithm that identifies and decomposes a median graph of a triangulation of a 2-dimensional (2D) oriented bordered surface and in addition restores all corresponding triangulation whenever they exist. The algorithm…

Combinatorics · Mathematics 2010-07-13 Weiwen Gu

A median graph is a connected graph, such that for any three vertices $u,v,w$ there is exactly one vertex $x$ that lies simultaneously on a shortest $(u,v)$-path, a shortest $(v,w)$-path and a shortest $(w,u)$-path. Examples of median…

Combinatorics · Mathematics 2016-01-29 Konstantinos Stavropoulos

We establish counting formulas and bijections for deformations of the braid arrangement. Precisely, we consider real hyperplane arrangements such that all the hyperplanes are of the form $x\_i-x\_j=s$ for some integer $s$. Classical…

Combinatorics · Mathematics 2021-06-15 Olivier Bernardi

In this paper, we introduce two families of planar and self-similar graphs which have small-world properties. The constructed models are based on an iterative process where each step of a certain formulation of modules results in a final…

Combinatorics · Mathematics 2024-04-19 Muhammed Alaa Morsy , Mohamed Anwar , Abdallah Aboutahoun

We deal with the asymptotic enumeration of combinatorial structures on planar maps. Prominent instances of such problems are the enumeration of spanning trees, bipartite perfect matchings, and ice models. The notion of orientations with…

Combinatorics · Mathematics 2007-09-06 S. Felsner , F. Zickfeld

A tanglegram consists of two rooted binary trees and a perfect matching between their leaves, and a planar tanglegram is one that admits a layout with no crossings. We show that the problem of generating planar tanglegrams uniformly at…

Combinatorics · Mathematics 2023-04-13 Alexander E. Black , Kevin Liu , Alex Mcdonough , Garrett Nelson , Michael C. Wigal , Mei Yin , Youngho Yoo

Uniform spanning trees are a statistical model obtained by taking the set of all spanning trees on a given graph (such as a portion of a cubic lattice in d dimensions), with equal probability for each distinct tree. Some properties of such…

Statistical Mechanics · Physics 2009-11-10 N. Read

Let $G$ be a 3-connected planar graph. Define the co-tree of a spanning tree $T$ of $G$ as the graph induced by the dual edges of $E(G)-E(T)$. The well-known cut-cycle duality implies that the co-tree is itself a tree. Let a $k$-tree be a…

Discrete Mathematics · Computer Science 2024-06-05 Christian Ortlieb , Jens M. Schmidt

We consider the probability that a spanning tree chosen uniformly at random from a graph can be partitioned into a fixed number $k$ of trees of equal size by removing $k-1$ edges. In that case, the spanning tree is called {\em splittable}.…

Data Structures and Algorithms · Computer Science 2026-02-25 David Gillman , Jacob Platnick , Dana Randall

Reduction trees are a way of encoding a substitution procedure dictated by the relations of an algebra. We use reduction trees in the subdivision algebra to construct canonical triangulations of flow polytopes which are shellable. We…

Combinatorics · Mathematics 2015-02-16 Karola Mészáros

For a simple drawing $D$ of the complete graph $K_n$, two (plane) subdrawings are compatible if their union is plane. Let $\mathcal{T}_D$ be the set of all plane spanning trees on $D$ and $\mathcal{F}(\mathcal{T}_D)$ be the compatibility…

The twin-width of a graph measures its distance to co-graphs and generalizes classical width concepts such as tree-width or rank-width. Since its introduction in 2020 (Bonnet et. al. 2020), a mass of new results has appeared relating twin…

Combinatorics · Mathematics 2024-11-21 Irene Heinrich , Simon Raßmann