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Motivated by the concept of well-covered graphs, we define a graph to be well-bicovered if every vertex-maximal bipartite subgraph has the same order (which we call the bipartite number). We first give examples of them, compare them with…

Combinatorics · Mathematics 2019-09-18 Wayne Goddard , Kirsti Kuenzel , Eileen Melville

A consistent path system in a graph $G$ is an intersection-closed collection of paths, with exactly one path between any two vertices in $G$. We call $G$ metrizable if every consistent path system in it is the system of geodesic paths…

Combinatorics · Mathematics 2023-11-17 Maria Chudnovsky , Daniel Cizma , Nati Linial

A class of graphs is $\chi$-bounded if there exists a function $f:\mathbb N\rightarrow \mathbb N$ such that for every graph $G$ in the class and an induced subgraph $H$ of $G$, if $H$ has no clique of size $q+1$, then the chromatic number…

Combinatorics · Mathematics 2019-01-16 Hojin Choi , O-joung Kwon , Sang-il Oum , Paul Wollan

A colouring of a graph is "nonrepetitive" if for every path of even order, the sequence of colours on the first half of the path is different from the sequence of colours on the second half. We show that planar graphs have nonrepetitive…

Combinatorics · Mathematics 2022-01-24 Vida Dujmović , Louis Esperet , Gwenaël Joret , Bartosz Walczak , David R. Wood

For a flexible labeling of a graph, it is possible to construct infinitely many non-equivalent realizations keeping the distances of connected points constant. We give a combinatorial characterization of graphs that have flexible labelings.…

Combinatorics · Mathematics 2019-09-17 Georg Grasegger , Jan Legerský , Josef Schicho

A graph is path-pairable if for any pairing of its vertices there exist edge disjoint paths joining the vertices in each pair. We obtain sharp bounds on the maximum possible diameter of path-pairable graphs which either have a given number…

Combinatorics · Mathematics 2017-07-14 Antonio Girao , Gabor Meszaros , Kamil Popielarz , Richard Snyder

We say that a graph $H$ dominates another graph $H'$ if the number of homomorphisms from $H'$ to any graph $G$ is dominated, in an appropriate sense, by the number of homomorphisms from $H$ to $G$. We study the family of dominating graphs,…

Combinatorics · Mathematics 2024-11-27 David Conlon , Joonkyung Lee

A graph is IC-planar if it admits a drawing in the plane with at most one crossing per edge and such that two pairs of crossing edges share no common end vertex. IC-planarity specializes both NIC-planarity, which allows a pair of crossing…

Discrete Mathematics · Computer Science 2017-07-28 Christian Bachmaier , Franz J. Brandenburg , Kathrin Hanauer

We investigate the maximum size of graph families on a common vertex set of cardinality $n$ such that the symmetric difference of the edge sets of any two members of the family satisfies some prescribed condition. We solve the problem…

Combinatorics · Mathematics 2022-04-05 Noga Alon , Anna Gujgiczer , János Körner , Aleksa Milojević , Gábor Simonyi

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

A graph is $H$-free if it has no induced subgraph isomorphic to $H$. We continue a study into the boundedness of clique-width of subclasses of perfect graphs. We identify five new classes of $H$-free split graphs whose clique-width is…

Discrete Mathematics · Computer Science 2015-09-16 Andreas Brandstädt , Konrad K. Dabrowski , Shenwei Huang , Daniël Paulusma

In this paper, we reveal an intriguing relationship between two seemingly unrelated notions: letter graphs and geometric grid classes of permutations. An important property common for both of them is well-quasi-orderability, implying, in a…

Combinatorics · Mathematics 2018-05-01 Bogdan Alecu , Vadim Lozin , Dominique de Werra , Viktor Zamaraev

A graph is 1-planar if it can be drawn on the plane so that each edge is crossed by no more than one other edge (and any pair of crossing edges cross only once). A non-1-planar graph $G$ is minimal if the graph $G-e$ is 1-planar for every…

Combinatorics · Mathematics 2011-10-24 Vladimir P. Korzhik , Bojan Mohar

A random rooted graph is said to be sofic if it is the Benjamini-Schramm limit of a sequence of finite graphs. Given any finite graph $H$, we prove that every one-ended, unimodular random rooted graph that does not have H as a minor must be…

Combinatorics · Mathematics 2025-10-14 Oriol Solé-Pi

The implicit graph conjecture states that every sufficiently small, hereditary graph class has a labeling scheme with a polynomial-time computable label decoder. We approach this conjecture by investigating classes of label decoders defined…

Computational Complexity · Computer Science 2018-02-02 Maurice Chandoo

In this paper, an effort is made to classify which prime character degree graphs having eight vertices occur for some finite solvable group. To approach this, we compile known results and constructions from the literature which are used to…

Group Theory · Mathematics 2026-04-07 Mark L. Lewis , Andrew Summers

Clique-width is a well-studied graph parameter owing to its use in understanding algorithmic tractability: if the clique-width of a graph class ${\cal G}$ is bounded by a constant, a wide range of problems that are NP-complete in general…

Combinatorics · Mathematics 2021-12-23 Konrad K. Dabrowski , Matthew Johnson , Daniël Paulusma

A graph is 1-planar if it can be drawn on a plane so that each edge is crossed by at most one other edge. In this paper, we first give a useful structural theorem for 1-planar graphs, and then apply it to the list edge and list total…

Combinatorics · Mathematics 2019-12-17 Xin Zhang , Bei Niu , Jiguo Yu

A class of graphs is nowhere dense if for every integer r there is a finite upper bound on the size of cliques that occur as (topological) r-minors. We observe that this tameness notion from algorithmic graph theory is essentially the…

Logic · Mathematics 2010-11-18 Hans Adler , Isolde Adler

Tree decompositions of graphs are of fundamental importance in structural and algorithmic graph theory. Planar decompositions generalise tree decompositions by allowing an arbitrary planar graph to index the decomposition. We prove that…

Combinatorics · Mathematics 2007-06-13 David R. Wood , Jan Arne Telle
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