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A graph is said to be edge-transitive if its automorphism group acts transitively on its edges. It is known that edge-transitive graphs are either vertex-transitive or bipartite. In this paper we present a complete classification of all…

Combinatorics · Mathematics 2019-11-13 Heather A. Newman , Hector Miranda , Darren A. Narayan

The subdivision graph $S(\Sigma)$ of a connected graph $\Sigma$ is constructed by adding a vertex in the middle of each edge. In a previous paper written with Cheryl E. Praeger, we characterised the graphs $\Sigma$ such that $S(\Sigma)$ is…

Combinatorics · Mathematics 2011-03-31 Ashraf Daneshkhah , Alice Devillers

For each of the 14 classes of edge-transitive maps described by Graver and Watkins, necessary and sufficient conditions are given for a group to be the automorphism group of a map, or of an orientable map without boundary, in that class.…

Combinatorics · Mathematics 2019-06-26 Gareth A. Jones

For a subset $ S $ of $ \mathbb R^d$, $ S$-graphs are the intersection graphs of specific transformations of $ S $. The class of Burling graphs is a class of triangle-free graphs with arbitrarily large chromatic number that has attracted…

Combinatorics · Mathematics 2023-08-30 Pegah Pournajafi

A transitive graph is 2-dimensional if it can be represented as the intersection of two linear orders. Such representations make answering of reachability queries trivial, and allow many problems that are NP-hard on arbitrary graphs to be…

Discrete Mathematics · Computer Science 2019-04-09 Henning Koehler

The all-terminal reliability of a graph $G$ is the probability that $G$ remains connected when each edge fails independently with probability $p$. For fixed $n$ and $m$, the uniformly most reliable problem asks which graph with $n$ vertices…

Combinatorics · Mathematics 2026-03-03 Rotem Brand , Reuven Cohen , Simi Haber , Baruch Barzel

For a positive real number $p$, the $p$-norm $\left\lVert G \right\rVert_p$ of a graph $G$ is the sum of the $p$-th powers of all vertex degrees. We study the maximum $p$-norm $\mathrm{ex}_{p}(n,F)$ of $F$-free graphs on $n$ vertices.…

Combinatorics · Mathematics 2025-03-04 Jun Gao , Xizhi Liu , Jie Ma , Oleg Pikhurko

A graph is said to be {\em vertex-transitive non-Cayley} if its full automorphism group acts transitively on its vertices and contains no subgroups acting regularly on its vertices. In this paper, a complete classification of cubic…

Combinatorics · Mathematics 2017-05-15 Wei-Juan Zhang , Yan-Quan Feng , Jin-Xin Zhou

We study dilations of finite tuples of normal, completely positive and completely contractive maps (which we call CP-maps) acting on a von Neumann algebra, and commuting according to a graph G. We show that if G is acyclic, then a tuple…

Operator Algebras · Mathematics 2021-08-16 Alexander Vernik

Aldous [1] asked whether every graph in which the distribution of the return time of random is independent of the starting vertex must be transitive. We remark that this question can be reduced into a purely graph-theoretic one that had…

Combinatorics · Mathematics 2012-11-27 Agelos Georgakopoulos

Based on earlier work by Carlen-Maas and the second- and third-named author, we introduce the notion of intertwining curvature lower bounds for graphs and quantum Markov semigroups. This curvature notion is stronger than both Bakry-\'Emery…

Functional Analysis · Mathematics 2024-01-11 Florentin Münch , Melchior Wirth , Haonan Zhang

Starting from context-free inverse graphs, we introduce a new class of groups and study their structural properties. We establish closure properties, show that their co-word problems are context-free, analyze torsion elements, and realize…

Group Theory · Mathematics 2025-11-18 Daniele D'Angeli , Francesco Matucci , Davide Perego , Emanuele Rodaro

We study a special class of graphs with a strong transience feature called uniform transience. We characterize uniform transience via a Feller-type property and via validity of an isoperimetric inequality. We then give a further…

Functional Analysis · Mathematics 2014-12-03 Matthias Keller , Daniel Lenz , Marcel Schmidt , Radosław K. Wojciechowski

Karp conjectured that all nontrivial monotone graph properties are evasive. This was proved for n a prime power, and n=6, where n is the number of graph vertices, by Kahn, Saks, and Sturtevant. We give a complete description of which…

Combinatorics · Mathematics 2007-05-23 Alexander Engström

The fully dynamic transitive closure problem asks to maintain reachability information in a directed graph between arbitrary pairs of vertices, while the graph undergoes a sequence of edge insertions and deletions. The problem has been…

Data Structures and Algorithms · Computer Science 2020-02-04 Kathrin Hanauer , Monika Henzinger , Christian Schulz

A crossing-free morph is a continuous deformation between two graph drawings that preserves straight-line pairwise noncrossing edges. Motivated by applications in 3D morphing problems, we initiate the study of morphing graph drawings in the…

Computational Geometry · Computer Science 2026-01-21 Oksana Firman , Tim Hegemann , Boris Klemz , Felix Klesen , Marie Diana Sieper , Alexander Wolff , Johannes Zink

A graph is said to be a bi-Cayley graph over a group H if it admits H as a group of automorphisms acting semiregularly on its vertices with two orbits. For a prime p, we call a bi-Cayley graph over a metacyclic p-group a bi-p-metacirculant.…

Combinatorics · Mathematics 2016-10-25 Yan-Li Qin , Jin-Xin Zhou

We propose a definition of graph subshifts of finite type that can be seen as extending both the notions of subshifts of finite type from classical symbolic dynamics and finitely presented groups from combinatorial group theory. These are…

Discrete Mathematics · Computer Science 2026-05-05 Pablo Arrighi , Amélia Durbec , Pierre Guillon

We investigate generalisations of the classical percolation critical probabilities $p_c$, $p_T$ and the critical probability $\tilde{p_c}$ defined by Duminil-Copin and Tassion (2015) to bounded degree unimodular random graphs. We further…

Probability · Mathematics 2020-05-14 Dorottya Beringer , Gábor Pete , Ádám Timár

In this paper we introduce the definition of transitivity for oriented 3-hypergraphs in order to study partial and complete cyclic orders. This definition allow us to give sufficient conditions on a partial cyclic order to be totally…

Combinatorics · Mathematics 2012-10-26 Natalia Garcia-Colin , Amanda Montejano , Luis Montejano , Deborah Oliveros