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Given a connected outerplanar graph G of pathwidth p, we give an algorithm to add edges to G to get a supergraph of G, which is 2-vertex-connected, outerplanar and of pathwidth O(p). This settles an open problem raised by Biedl, in the…

Discrete Mathematics · Computer Science 2014-01-03 Jasine Babu , Manu Basavaraju , L. Sunil Chandran , Deepak Rajendraprasad

It is known that many networks modeling real-life complex systems are small-word (large local clustering and small diameter) and scale-free (power law of the degree distribution), and very often they are also hierarchical. Although most of…

Combinatorics · Mathematics 2016-08-09 C. Dalfó , M. A. Fiol

In a recent paper, Kwon and Oum claim that every graph of bounded rank-width is a pivot-minor of a graph of bounded tree-width (while the converse has been known true already before). We study the analogous questions for "depth" parameters…

Discrete Mathematics · Computer Science 2014-03-28 Petr Hliněný , O-joung Kwon , Jan Obdržálek , Sebastian Ordyniak

We consider the problem of finding a subgraph of a given graph which minimizes the sum of given functions at vertices evaluated at their subgraph degrees. While the problem is NP-hard already when all functions are the same, we show that it…

Combinatorics · Mathematics 2023-05-30 Shmuel Onn

We show that many graphs with bounded treewidth can be described as subgraphs of the strong product of a graph with smaller treewidth and a bounded-size complete graph. To this end, define the "underlying treewidth" of a graph class…

Understanding the structure of minor-free metrics, namely shortest path metrics obtained over a weighted graph excluding a fixed minor, has been an important research direction since the fundamental work of Robertson and Seymour. A…

Data Structures and Algorithms · Computer Science 2020-09-11 Vincent Cohen-Addad , Arnold Filtser , Philip N. Klein , Hung Le

We prove that every graph of rank-width $k$ is a pivot-minor of a graph of tree-width at most $2k$. We also prove that graphs of rank-width at most 1, equivalently distance-hereditary graphs, are exactly vertex-minors of trees, and graphs…

Combinatorics · Mathematics 2014-03-26 O-joung Kwon , Sang-il Oum

In this paper, we explore the design and analysis of regular bipartite graphs motivated by their application in low-density parity-check (LDPC) codes specifically with constrained girth and in the high-rate regime. We focus on the relation…

Information Theory · Computer Science 2025-06-16 Sheida Rabeti , Mohsen Moradi , Hessam Mahdavifar

We establish a list of characterizations of bounded twin-width for hereditary, totally ordered binary structures. This has several consequences. First, it allows us to show that a (hereditary) class of matrices over a finite alphabet either…

Classes of graphs with bounded expansion are a generalization of both proper minor closed classes and degree bounded classes. Such classes are based on a new invariant, the greatest reduced average density (grad) of G with rank r,…

Combinatorics · Mathematics 2007-05-23 Jaroslav Nesetril , Patrice Ossona De Mendez

We find precise asymptotic estimates for the number of planar maps and graphs with a condition on the minimum degree, and properties of random graphs from these classes. In particular we show that the size of the largest tree attached to…

Combinatorics · Mathematics 2018-06-12 Marc Noy , Lander Ramos

In this paper, we study knot diagrams for which the underlying graph has treewidth two. We give a linear time algorithm for the following problem: given a knot diagram of treewidth two, does it represent the unknot? We also show that for a…

Data Structures and Algorithms · Computer Science 2019-04-09 Hans L. Bodlaender , Benjamin Burton , Fedor V. Fomin , Alexander Grigoriev

This paper explores the structure of graphs defined by an excluded minor or an excluded odd minor through the lens of graph products and tree-decompositions. We prove that every graph excluding a fixed odd minor is contained in the strong…

Combinatorics · Mathematics 2024-10-29 Chun-Hung Liu , Sergey Norin , David R. Wood

Several different measures for digraph width have appeared in the last few years. However, none of them shares all the "nice" properties of treewidth: First, being \emph{algorithmically useful} i.e. admitting polynomial-time algorithms for…

Discrete Mathematics · Computer Science 2016-08-14 Robert Ganian , Petr Hliněný , Joachim Kneis , Daniel Meister , Jan Obdržálek , Peter Rossmanith , Somnath Sikdar

A graph $G$ contains a graph $H$ as an induced minor if $H$ can be obtained from $G$ after vertex deletions and edge contractions. We show that for every $k$-vertex planar graph $H$, every graph $G$ excluding $H$ as an induced minor and…

Combinatorics · Mathematics 2024-07-23 Édouard Bonnet , Jędrzej Hodor , Tuukka Korhonen , Tomáš Masařík

It was recently proved that every planar graph is a subgraph of the strong product of a path and a graph with bounded treewidth. This paper surveys generalisations of this result for graphs on surfaces, minor-closed classes, various…

Combinatorics · Mathematics 2021-02-18 Zdeněk Dvořák , Tony Huynh , Gwenaël Joret , Chun-Hung Liu , David R. Wood

This paper presents the novel `uniqueness tree' algorithm, as one possible method for determining whether two finite, undirected graphs are isomorphic. We prove that the algorithm has polynomial time complexity in the worst case, and that…

Discrete Mathematics · Computer Science 2016-06-22 Jonathan Gorard

We prove that the tree-width of graphs in a hereditary class defined by a finite set $F$ of forbidden induced subgraphs is bounded if and only if $F$ includes a complete graph, a complete bipartite graph, a tripod (a forest in which every…

Combinatorics · Mathematics 2021-01-06 Vadim Lozin , Igor Razgon

Twin-width is a recently introduced graph parameter with applications in algorithmics, combinatorics, and finite model theory. For graphs of bounded degree, finiteness of twin-width is preserved by quasi-isometry. Thus, through Cayley…

Group Theory · Mathematics 2022-07-18 Édouard Bonnet , Colin Geniet , Romain Tessera , Stéphan Thomassé

Tree-width and path-width are well-known graph parameters. Many NP-hard graph problems allow polynomial-time solutions, when restricted to graphs of bounded tree-width or bounded path-width. In this work, we study the behavior of tree-width…

Data Structures and Algorithms · Computer Science 2024-06-14 Frank Gurski , Robin Weishaupt
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