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Counterfactual examples have emerged as an effective approach to produce simple and understandable post-hoc explanations. In the context of graph classification, previous work has focused on generating counterfactual explanations by…

Machine Learning · Computer Science 2023-07-28 Carlo Abrate , Giulia Preti , Francesco Bonchi

We consider various regular graphs defined on the set of elements of given rank of a finite polar space. It is likely that no two such graphs, of the same kind but defined for different ranks, can have the same degree. We shall prove this…

Combinatorics · Mathematics 2021-05-27 Antonio Pasini

In this note we give two examples of partially commutative subgroups of partially commutative groups. Our examples are counterexamples to the Extension Graph Conjecture and to the Weakly Chordal Conjecture of Kim and Koberda, \cite{KK}. On…

Group Theory · Mathematics 2013-06-14 Montserrat Casals-Ruiz , Andrew Duncan , Ilya Kazachkov

A strong edge-coloring of a graph $G$ is an edge-coloring in which every color class is an induced matching, and the strong chromatic index $\chi_s'(G)$ is the minimum number of colors needed in strong edge-colorings of $G$. A graph is…

Combinatorics · Mathematics 2023-01-31 Gexin Yu , Rachel Yu

A natural way to represent on the plane both a planar graph and its dual is to follow the definition of the dual, thus, to place vertices inside their corresponding primal faces, and to draw the dual edges so that they only cross their…

Computational Geometry · Computer Science 2015-05-12 Tamara Mchedlidze

Given a graph $F$, a graph $G$ is weakly $F$-saturated if all non-edges of $G$ can be added in some order so that each new edge introduces a copy of $F$. The weak saturation number $\operatorname{wsat}(n, F)$ is the minimum number of edges…

Combinatorics · Mathematics 2026-02-10 Ruben Ascoli , Xiaoyu He

L. Soukup formulated an abstract framework in his introductory paper for proving theorems about uncountable graphs by subdividing them by an increasing continuous chain of elementary submodels. The applicability of this method relies on the…

Combinatorics · Mathematics 2023-07-13 Attila Joó

The weak variant of Hanani-Tutte theorem says that a graph is planar, if it can be drawn in the plane so that every pair of edges cross an even number of times. Moreover, we can turn such a drawing into an embedding without changing the…

Computational Geometry · Computer Science 2016-05-06 Radoslav Fulek

A graph $G$ is weakly $\gamma$-closed if every induced subgraph of $G$ contains one vertex $v$ such that for each non-neighbor $u$ of $v$ it holds that $|N(u)\cap N(v)|<\gamma$. The weak closure $\gamma(G)$ of a graph, recently introduced…

Discrete Mathematics · Computer Science 2022-11-04 Tomohiro Koana , Christian Komusiewicz , Frank Sommer

This article investigates structural, geometrical, and topological characterizations and properties of weakly modular graphs and of cell complexes derived from them. The unifying themes of our investigation are various `nonpositive…

Metric Geometry · Mathematics 2022-03-03 Jérémie Chalopin , Victor Chepoi , Hiroshi Hirai , Damian Osajda

This paper discusses the semantics of weighted argumentation graphs that are biplor, i.e. contain both attacks and support graphs. The work builds on previous work by Amgoud, Ben-Naim et. al., which presents and compares several semantics…

Artificial Intelligence · Computer Science 2016-12-26 Till Mossakowski , Fabian Neuhaus

We introduce weak oddness $\omega_{\textrm w}$, a new measure of uncolourability of cubic graphs, defined as the least number of odd components in an even factor. For every bridgeless cubic graph $G$, $\rho(G)\le\omega_{\textrm…

Discrete Mathematics · Computer Science 2016-02-10 Robert Lukoťka , Ján Mazák

A graph is 1-planar if it admits a drawing in the plane such that each edge is crossed at most once. Let G be a bipartite 1-planar graph with partite sets X and Y. A 1-disk OX drawing of G is a 1-planar drawing such that all vertices of X…

Combinatorics · Mathematics 2025-07-29 Guiping Wang

Let $\perp$ be a unitary polarity of a finite projective plane $\pi$ of order $q^2$. The unitary polarity graph is the graph with vertex set the points of $\pi$ where two vertices $x$ and $y$ are adjacent if $x \in y^\perp$. We show that a…

Combinatorics · Mathematics 2018-05-03 Sam Mattheus , Francesco Pavese

We provide a new family of $K_k$-free pseudorandom graphs with edge density $\Theta(n^{-1/(k-1)})$, matching a recent construction due to Bishnoi, Ihringer and Pepe. As in the former result, the idea is to use large subgraphs of polarity…

Combinatorics · Mathematics 2021-05-11 Sam Mattheus , Francesco Pavese

The thickness $\theta(G)$ of a graph $G$ is the minimum number of planar spanning subgraphs into which the graph $G$ can be decomposed. As a topological invariant of a graph, it is a measurement of the closeness to planarity of a graph, and…

Combinatorics · Mathematics 2012-02-01 Yan Yang , Xiangheng Kong

We define the limiting density of a minor-closed family of simple graphs F to be the smallest number k such that every n-vertex graph in F has at most kn(1+o(1)) edges, and we investigate the set of numbers that can be limiting densities.…

Combinatorics · Mathematics 2010-10-18 David Eppstein

The $\{K_2,C_n\}$-factor of a graph is a spanning subgraph whose each component is either $K_2$ or $C_n$. In this paper, a sufficient condition with regard to tight toughness, isolated toughness and binding number bounds to guarantee the…

Combinatorics · Mathematics 2022-04-12 Xiaxia Guan , Tianlong Ma , Chao Shi

We prove that for any weakly convergent sequence of finite graphs with bounded vertex degrees, there exists a topological limit graphing.

Combinatorics · Mathematics 2007-05-23 Gabor Elek

We give a short, self-contained, and easily verifiable proof that determining the outerthickness of a general graph is NP-hard. This resolves a long-standing open problem on the computational complexity of outerthickness. Moreover, our…

Computational Complexity · Computer Science 2026-02-10 Pin-Hsian Lee , Te-Cheng Liu , Meng-Tsung Tsai