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Computing a Euclidean minimum spanning tree of a set of points is a seminal problem in computational geometry and geometric graph theory. We combine it with another classical problem in graph drawing, namely computing a monotone geometric…

Computational Geometry · Computer Science 2024-11-26 Emilio Di Giacomo , Walter Didimo , Eleni Katsanou , Lena Schlipf , Antonios Symvonis , Alexander Wolff

Given two $n$-vertex graphs $G_1$ and $G_2$ of bounded treewidth, is there an $n$-vertex graph $G$ of bounded treewidth having subgraphs isomorphic to $G_1$ and $G_2$? Our main result is a negative answer to this question, in a strong…

Combinatorics · Mathematics 2024-02-13 Bogdan Alecu , Vadim Lozin , Daniel A. Quiroz , Roman Rabinovich , Igor Razgon , Viktor Zamaraev

We show that every graph with pathwidth strictly less than $a$ that contains no path on $2^b$ vertices as a subgraph has treedepth at most $10ab$. The bound is best possible up to a constant factor.

Combinatorics · Mathematics 2024-11-05 Meike Hatzel , Gwenaël Joret , Piotr Micek , Marcin Pilipczuk , Torsten Ueckerdt , Bartosz Walczak

We consider in this paper the problem of discovering, via a traceroute algorithm, the topology of a network, whose graph is spanned by an infinite branching process. A subset of nodes is selected according to some criterion. As a measure of…

Networking and Internet Architecture · Computer Science 2009-08-25 Fabrice Guillemin , Philippe Robert

Enumerating the minimal hitting sets of a hypergraph is a problem which arises in many data management applications that include constraint mining, discovering unique column combinations, and enumerating database repairs. Previously, Eiter…

Databases · Computer Science 2025-01-28 Batya Kenig , Dan Shlomo Mizrahi

The connected tree-width of a graph is the minimum width of a tree-decomposition whose parts induce connected subgraphs. Long cycles are examples of graphs that have small tree-width but large connected tree-width. We show that a graph has…

Combinatorics · Mathematics 2015-10-15 Reinhard Diestel , Malte Müller

We show that planar graphs have bounded queue-number, thus proving a conjecture of Heath, Leighton and Rosenberg from 1992. The key to the proof is a new structural tool called layered partitions, and the result that every planar graph has…

Discrete Mathematics · Computer Science 2020-08-11 Vida Dujmović , Gwenaël Joret , Piotr Micek , Pat Morin , Torsten Ueckerdt , David R. Wood

We conjecture that every $n$-vertex graph of minimum degree at least $\frac k2$ and maximum degree at least $2k$ contains all trees with $k$ edges as subgraphs. We prove an approximate version of this conjecture for trees of bounded degree…

Combinatorics · Mathematics 2018-08-29 Guido Besomi , Matías Pavez-Signé , Maya Stein

Aboulker, Adler, Kim, Sintiari, and Trotignon conjectured that every graph with bounded maximum degree and large treewidth must contain, as an induced subgraph, a large subdivided wall, or the line graph of a large subdivided wall. This…

Combinatorics · Mathematics 2022-05-19 Bogdan Alecu , Maria Chudnovsky , Kristina Vušković

Many of the tools developed for the theory of tree-decompositions of graphs do not work for directed graphs. In this paper we show that some of the most basic tools do work in the case where the model digraph is a directed path. Using these…

Combinatorics · Mathematics 2017-11-03 Joshua Erde

We prove that a connected graph has linear rank-width 1 if and only if it is a distance-hereditary graph and its split decomposition tree is a path. An immediate consequence is that one can decide in linear time whether a graph has linear…

Discrete Mathematics · Computer Science 2014-07-09 Binh-Minh Bui-Xuan , Mamadou Moustapha Kanté , Vincent Limouzy

As a major step in their proof of Wagner's conjecture, Robertson and Seymour showed that every graph not containing a fixed graph $H$ as a minor has a tree-decomposition in which each torso is almost embeddable in a surface of bounded…

Combinatorics · Mathematics 2018-07-04 Joshua Erde , Daniel Weißauer

Knuth and Moore presented a theoretical lower bound on the number of leaves that any fixed-depth minimax tree-search algorithm traversing a uniform tree must explore, the so-called minimal tree. Since real-life minimax trees are not…

Artificial Intelligence · Computer Science 2014-04-08 Aske Plaat , Jonathan Schaeffer , Wim Pijls , Arie de Bruin

Rank-width is a width parameter of graphs describing whether it is possible to decompose a graph into a tree-like structure by `simple' cuts. This survey aims to summarize known algorithmic and structural results on rank-width of graphs.

Combinatorics · Mathematics 2018-05-16 Sang-il Oum

This paper investigates some properties of the number of subtrees of a tree with given degree sequence. These results are used to characterize trees with the given degree sequence that have the largest number of subtrees, which generalizes…

Combinatorics · Mathematics 2012-09-04 Xiu-Mei Zhang , Xiao-Dong Zhang , Daniel Gray , Hua Wang

Let $G$ be an undirected graph. We say that $G$ contains a ladder of length $k$ if the $2 \times (k+1)$ grid graph is an induced subgraph of $G$ that is only connected to the rest of $G$ via its four cornerpoints. We prove that if all the…

Combinatorics · Mathematics 2024-01-31 Steven Chaplick , Steven Kelk , Ruben Meuwese , Matus Mihalak , Georgios Stamoulis

The linear induced matching width (LMIM-width) of a graph is a width parameter defined by using the notion of branch-decompositions of a set function on ternary trees. In this paper we study output-polynomial enumeration algorithms on…

Data Structures and Algorithms · Computer Science 2015-09-16 Petr A. Golovach , Pinar Heggernes , Mamadou Moustapha Kanté , Dieter Kratsch , Sigve H. Sæther , Yngve Villanger

We discuss a notion of convergence for binary trees that is based on subtree sizes. In analogy to recent developments in the theory of graphs, posets and permutations we investigate some general aspects of the topology, such as a…

Combinatorics · Mathematics 2024-02-14 Rudolf Grübel

A rooted tree is balanced if the degree of a vertex depends only on its distance to the root. In this paper we determine the sharp threshold for the appearance of a large family of balanced spanning trees in the random geometric graph…

Combinatorics · Mathematics 2023-03-28 Alberto Espuny Díaz , Lyuben Lichev , Dieter Mitsche , Alexandra Wesolek

When considering the number of subtrees of trees, the extremal structures which maximize this number among binary trees and trees with a given maximum degree lead to some interesting facts that correlate to other graphical indices in…

Combinatorics · Mathematics 2012-10-11 Xiu-Mei Zhang , Xiao-Dong Zhang , Daniel Gray , Hua Wang