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Treedepth decomposition has several practical applications and can be used to speed up many parameterized algorithms. There are several works aiming to design a scalable algorithm to compute exact treedepth decompositions. Those include…

Data Structures and Algorithms · Computer Science 2020-12-15 Zijian Xu , Vorapong Suppakitpaisarn

The independence number of a tree decomposition is the maximum of the independence numbers of the subgraphs induced by its bags. The tree-independence number of a graph is the minimum independence number of a tree decomposition of it.…

Data Structures and Algorithms · Computer Science 2025-09-11 Clément Dallard , Fedor V. Fomin , Petr A. Golovach , Tuukka Korhonen , Martin Milanič

Menger's theorem tells us that if $S,T$ are sets of vertices in a graph $G$, then (for $k\ge0$) either there are $k+1$ vertex-disjoint paths between $S$ and $T$, or there is a set of $k$ vertices separating $S$ and $T$. But what if we want…

Combinatorics · Mathematics 2025-09-11 Tung Nguyen , Alex Scott , Paul Seymour

Let $G=(V,E)$ and $H$ be two graphs. Packing problem is to find in $G$ the largest number of independent subgraphs each of which is isomorphic to $H$. Let $U\subset{V}$. If the graph $G-U$ has no subgraph isomorphic to $H$, $U$ is a cover…

Combinatorics · Mathematics 2013-09-17 Jia Zhao , Jianfeng Guan , Changqiao Xu , Hongke Zhang

In this paper, we give a constructive proof of the fact that the treewidth of a graph is at most its divisorial gonality. The proof gives a polynomial time algorithm to construct a tree decomposition of width at most $k$, when an effective…

Discrete Mathematics · Computer Science 2020-05-13 Hans L. Bodlaender , Josse van Dobben de Bruyn , Dion Gijswijt , Harry Smit

A graph $G$ contains a graph $H$ as an induced minor if $H$ can be obtained from $G$ by vertex deletions and edge contractions. The class of $H$-induced-minor-free graphs generalizes the class of $H$-minor-free graphs, but unlike…

Data Structures and Algorithms · Computer Science 2023-08-10 Tuukka Korhonen , Daniel Lokshtanov

For undirected graphs $G=(V,E)$ and $G_0=(V_0,E_0)$, say that $G$ is a region intersection graph over $G_0$ if there is a family of connected subsets $\{ R_u \subseteq V_0 : u \in V \}$ of $G_0$ such that $\{u,v\} \in E \iff R_u \cap R_v…

Combinatorics · Mathematics 2017-07-28 James R. Lee

Mader [J. Graph Theory 65 (2010) 61-69] conjectured that for every positive integer $k$ and every finite tree $T$ with order $m$, every $k$-connected, finite graph $G$ with $\delta(G)\geq \lfloor\frac{3}{2}k\rfloor+m-1$ contains a subtree…

Combinatorics · Mathematics 2017-10-10 Yingzhi Tian , Hong-Jian Lai , Liqiong Xu , Jixiang Meng

For a tree decomposition $\mathcal{T}$ of a graph $G$, by $\mu(\mathcal{T})$ we denote the size of a largest induced matching in $G$ all of whose edges intersect one bag of $\mathcal{T}$. Induced matching treewidth of a graph $G$ is the…

Data Structures and Algorithms · Computer Science 2024-02-27 Paloma T. Lima , Martin Milanič , Peter Muršič , Karolina Okrasa , Paweł Rzążewski , Kenny Štorgel

We prove two results relating the basis number of a graph $G$ to path decompositions of $G$. Our first result shows that the basis number of a graph is at most four times its pathwidth. Our second result shows that, if a graph $G$ has a…

Combinatorics · Mathematics 2026-01-21 Babak Miraftab , Pat Morin , Yelena Yuditsky

The component size of a graph is the maximum number of edges in any connected component of the graph. Given a graph $G$ and two integers $k$ and $c$, $(k,c)$-Decomposition is the problem of deciding whether $G$ admits an edge partition into…

Computational Complexity · Computer Science 2021-10-05 Rain Jiang , Kai Jiang , Minghui Jiang

A path (resp. cycle) decomposition of a graph $G$ is a set of edge-disjoint paths (resp. cycles) of $G$ that covers the edge set of $G$. Gallai (1966) conjectured that every graph on $n$ vertices admits a path decomposition of size at most…

Combinatorics · Mathematics 2017-06-15 Fábio Botler , Maycon Sambinelli , Rafael S. Coelho , Orlando Lee

The tree breadth ${\rm tb}(G)$ of a connected graph $G$ is the smallest non-negative integer $\rho$ such that $G$ has a tree decomposition whose bags all have radius at most $\rho$. We show that, given a connected graph $G$ of order $n$ and…

Combinatorics · Mathematics 2020-02-28 Oliver Bendele , Dieter Rautenbach

Considering systems of separations in a graph that separate every pair of a given set of vertex sets that are themselves not separated by these separations, we determine conditions under which such a separation system contains a nested…

Combinatorics · Mathematics 2014-09-02 Johannes Carmesin , Reinhard Diestel , Fabian Hundertmark , Maya Stein

An old conjecture of Ringel states that every tree with $m$ edges decomposes the complete graph $K_{2m+1}$. The best known lower bound for the order of a complete graph which admits a decomposition by every given tree with $m$ edges is…

Combinatorics · Mathematics 2015-12-08 Anna Lladó

A $k$-block in a graph $G$ is a maximal set of at least $k$ vertices no two of which can be separated in $G$ by removing less than $k$ vertices. It is separable if there exists a tree-decomposition of adhesion less than $k$ of $G$ in which…

Combinatorics · Mathematics 2015-06-10 Johannes Carmesin , Pascal Gollin

A \emph{tree-partition} of a graph $G$ is a proper partition of its vertex set into `bags', such that identifying the vertices in each bag produces a forest. The \emph{tree-partition-width} of $G$ is the minimum number of vertices in a bag…

Combinatorics · Mathematics 2009-04-02 David R. Wood

This paper concerns fractional $K_s$-decompositions of multipartite graphs. For integers $r\ge s\ge 3$, we consider balanced $r$-partite graphs $G$ on $rn$ vertices. We establish necessary conditions for $G$ to admit a fractional…

Combinatorics · Mathematics 2026-04-29 Tao Feng , Hengrui Liu , Shikang Yu

We establish relations between the bandwidth and the treewidth of bounded degree graphs G, and relate these parameters to the size of a separator of G as well as the size of an expanding subgraph of G. Our results imply that if one of these…

Combinatorics · Mathematics 2009-10-19 Julia Böttcher , Klaas P. Pruessmann , Anusch Taraz , Andreas Würfl

We show that for any fixed dense graph G and bounded-degree tree T on the same number of vertices, a modest random perturbation of G will typically contain a copy of T . This combines the viewpoints of the well-studied problems of embedding…

Combinatorics · Mathematics 2025-05-30 Michael Krivelevich , Matthew Kwan , Benny Sudakov