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Let $G = (V,E)$ denote a simple graph with the vertex set $V$ and the edge set $E$. The profile of a vertex set $V'\subseteq V$ denotes the multiset of pairwise distances between the vertices of $V'$. Two disjoint subsets of $V$ are…

Combinatorics · Mathematics 2013-11-08 Radoslav Fulek , Slobodan Mitrović

Treewidth is a parameter that measures how tree-like a relational instance is, and whether it can reasonably be decomposed into a tree. Many computation tasks are known to be tractable on databases of small treewidth, but computing the…

Databases · Computer Science 2019-01-23 Silviu Maniu , Pierre Senellart , Suraj Jog

Hypergraph width measures are a class of hypergraph invariants important in studying the complexity of constraint satisfaction problems (CSPs). We present a general exact exponential algorithm for a large variety of these measures. A…

Computational Complexity · Computer Science 2011-06-24 Lukas Moll , Siamak Tazari , Marc Thurley

The $c$-packedness property, proposed in 2010, is a geometric property that captures the spatial distribution of a set of edges. Despite the recent interest in $c$-packedness, its utility has so far been limited to Fr\'echet distance…

Computational Geometry · Computer Science 2025-05-13 Lindsey Deryckere , Joachim Gudmundsson , André van Renssen , Yuan Sha , Sampson Wong

In Chordal/Interval Vertex Deletion we ask how many vertices one needs to remove from a graph to make it chordal (respectively: interval). We study these problems under the parameterization by treewidth $tw$ of the input graph $G$. On the…

Data Structures and Algorithms · Computer Science 2025-01-31 Michal Wlodarczyk

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

In this draft we prove an interesting structural property related to the problem of computing {\em all the best swap edges} of a {\em tree spanner} in unweighted graphs. Previous papers show that the maximum stretch factor of the tree where…

Discrete Mathematics · Computer Science 2018-07-11 Davide Bilò , Kleitos Papadopoulos

The following theorem is proved: For all $k$-connected graphs $G$ and $H$ each with at least $n$ vertices, the treewidth of the cartesian product of $G$ and $H$ is at least $k(n -2k+2)-1$. For $n\gg k$ this lower bound is asymptotically…

Combinatorics · Mathematics 2013-10-02 David R. Wood

Let $k$, $d$ be a positive integer, $G$ be a connected graph of order $n$, $T$ be a tree. The leaf distance of a tree is defined as the minimum distance between any two leaves. For $v\in V(T)$, the leaf degree of $v$ in $T$ is the number of…

Combinatorics · Mathematics 2025-01-15 Jifu Lin , Lihua You

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

It is proven that the connected pathwidth of any graph $G$ is at most $2\cdot\pw(G)+1$, where $\pw(G)$ is the pathwidth of $G$. The method is constructive, i.e. it yields an efficient algorithm that for a given path decomposition of width…

Discrete Mathematics · Computer Science 2021-03-05 Dariusz Dereniowski

A separation of a graph $G$ is a partition $(A_1, A_2, C)$ of $V(G)$ such that $A_1$ is anticomplete to $A_2$. A classic result from Robertson and Seymour's Graph Minors Project states that there is a correspondence between tree…

Combinatorics · Mathematics 2022-07-25 Tara Abrishami

The protection number of a vertex $v$ in a tree is the length of the shortest path from $v$ to any leaf contained in the maximal subtree where $v$ is the root. In this paper, we determine the distribution of the maximum protection number of…

Combinatorics · Mathematics 2024-11-26 Clemens Heuberger , Sarah J. Selkirk , Stephan Wagner

Treewidth is a graph parameter of fundamental importance to algorithmic and structural graph theory. This paper surveys several graph parameters tied to treewidth, including separation number, tangle number, well-linked number and Cartesian…

Combinatorics · Mathematics 2016-01-29 Daniel J. Harvey , David R. Wood

We give an algorithm that for an input n-vertex graph G and integer k>0, in time 2^[O(k)]n either outputs that the treewidth of G is larger than k, or gives a tree decomposition of G of width at most 5k+4. This is the first algorithm…

Data Structures and Algorithms · Computer Science 2013-04-24 Hans Bodlaender , Pål G. Drange , Markus S. Dregi , Fedor V. Fomin , Daniel Lokshtanov , Michał Pilipczuk

Decompositional parameters such as treewidth are commonly used to obtain fixed-parameter algorithms for NP-hard graph problems. For problems that are W[1]-hard parameterized by treewidth, a natural alternative would be to use a suitable…

Data Structures and Algorithms · Computer Science 2022-03-01 Cornelius Brand , Esra Ceylan , Christian Hatschka , Robert Ganian , Viktoriia Korchemna

Given an ordered partition $\Pi =\{P_1,P_2, ...,P_t\}$ of the vertex set $V$ of a connected graph $G=(V,E)$, the \emph{partition representation} of a vertex $v\in V$ with respect to the partition $\Pi$ is the vector…

Combinatorics · Mathematics 2014-02-10 Juan A. Rodriguez-Velazquez , Ismael G. Yero , Magdalena Lemanska

Berwanger et al. show that for every graph $G$ of size $n$ and DAG-width $k$ there is a DAG decomposition of width $k$ and size $n^{O(k)}$. This gives a polynomial time algorithm for determining the DAG-width of a graph for any fixed $k$.…

Discrete Mathematics · Computer Science 2020-04-01 Saeed Akhoondian Amiri , Stephan Kreutzer , Roman Rabinovich

Tree-width is an invaluable tool for computational problems on graphs. But often one would like to compute on other kinds of objects (e.g. decorated graphs or even algebraic structures) where there is no known tree-width analogue. Here we…

Combinatorics · Mathematics 2022-06-22 Benjamin Merlin Bumpus , Zoltan A. Kocsis

Every $k$-tree has book thickness at most $k+1$, and this bound is best possible for all $k\geq3$. Vandenbussche et al. (2009) proved that every $k$-tree that has a smooth degree-3 tree decomposition with width $k$ has book thickness at…

Combinatorics · Mathematics 2012-05-21 Vida Dujmović , David R. Wood