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We discuss a link between graph theory and geometry that arises when considering graph dynamical systems with odd interactions. The equilibrium set in such systems is not a collection of isolated points, but rather a union of manifolds,…

Dynamical Systems · Mathematics 2024-08-28 Davide Sclosa

When $S$ is a closed, orientable surface with genus $g(S) \geq 2$, we show that the automorphism group of the compression body graph $\mathcal{CB}(S)$ is the mapping class group. Here, vertices are compression bodies with exterior boundary…

Geometric Topology · Mathematics 2024-03-11 Ian Biringer , Nicholas G. Vlamis

We find a set of generators for the automorphism group of a graph product of finitely generated abelian groups entirely from a certain labeled graph. In addition, we find generators for the important subgroup of star-automorphisms defined…

Group Theory · Mathematics 2009-11-04 Luis Corredor , Mauricio Gutierrez

We give a simpler proof using automata theory of a recent result of Kapovich, Weidmann and Myasnikov according to which so-called benign graphs of groups preserve decidability of the generalized word problem. These include graphs of groups…

Group Theory · Mathematics 2009-05-28 Markus Lohrey , Benjamin Steinberg

We define a notion of quantum automorphism group of Graph C*-algebras for finite, connected graphs. Under the assumption that the underlying graph does not have any multiple edge or loop, the quantum automorphism group of underlying…

Operator Algebras · Mathematics 2018-10-11 Soumalya Joardar , Arnab Mandal

An embedding of a graph on an orientable surface is orientably-regular (or rotary, in an equivalent terminology) if the group of orientation-preserving automorphisms of the embedding is transitive (and hence regular) on incident vertex-edge…

Combinatorics · Mathematics 2023-11-17 Stefan Gyurki , Sona Pavlikova , Jozef Siran

In this paper, we prove that the maximal order of a semiregular element in the automorphism group of a cubic vertex-transitive graph X does not tend to infinity as the number of vertices of X tends to infinity. This gives a solution (in the…

Combinatorics · Mathematics 2019-02-20 Pablo Spiga

In this work, we consider an extension of graphical models to random graphs, trees, and other objects. To do this, many fundamental concepts for multivariate random variables (e.g., marginal variables, Gibbs distribution, Markov properties)…

Machine Learning · Statistics 2017-05-08 Neil Hallonquist

Let $G$ be a graph of order $n$ and let $k\in \{1,2,\ldots,n-1\}$. The $k$-token graph of $G$ is the graph, whose vertices are all the $k$-subsets of vertices of $G$, where two such $k$-sets are adjacent whenever their symmetric difference…

Combinatorics · Mathematics 2025-03-14 Ruy Fabila-Monroy , Ana Laura Trujillo-Negrete

It is shown, for a given graph group $G$, that the fixed point subgroup Fix$\,\varphi$ is finitely generated for every endomorphism $\varphi$ of $G$ if and only if $G$ is a free product of free abelian groups. The same conditions hold for…

Group Theory · Mathematics 2013-10-29 Emanuele Rodaro , Pedro V. Silva , Mihalis Sykiotis

We investigate families of graphs and graphons (graph limits) that are defined by a finite number of prescribed subgraph densities. Our main focus is the case when the family contains only one element, i.e., a unique structure is forced by…

Combinatorics · Mathematics 2013-08-23 Laszlo Lovasz , Balazs Szegedy

Given a countable abelian group $A$, we construct a row finite directed graph $\Gamma(A)$ such that the $K_{0}$-group of the graph $\textrm{C}^{\ast}$-algebra $\textrm{C}^{\ast}(\Gamma(A))$ is canonically isomorphic to $A$. Moreover, each…

Operator Algebras · Mathematics 2025-12-23 Swarnendu Datta , Debashish Goswami , Soumalya Joardar

We give a sharp bound on the number of automorphisms of a stable curve of a given genus and describe all curves attaining this bound.

Algebraic Geometry · Mathematics 2007-05-23 Michael A. van Opstall , Razvan Veliche

The analysis of large simple graphs with extreme values of the densities of edges and triangles has been extended to the statistical structure of typical graphs of fixed intermediate densities, by the use of large deviations of Erdoes-Renyi…

Probability · Mathematics 2022-03-31 Joe Neeman , Charles Radin , Lorenzo Sadun

We describe a technique to determine the automorphism group of a geometrically represented graph, by understanding the structure of the induced action on all geometric representations. Using this, we characterize automorphism groups of…

Combinatorics · Mathematics 2015-08-05 Pavel Klavík , Peter Zeman

We apply results proved in [Li19] to the linear order expansions of non-trivial free homogeneous structures and the universal n-linear order for $n\geq 2$, and prove the simplicity of their automorphism groups.

Group Theory · Mathematics 2020-09-08 Yibei Li

We show that infinitesimal automorphisms and infinitesimal deformations of parabolic geometries can be nicely described in terms of the twisted de-Rham sequence associated to a certain linear connection on the adjoint tractor bundle. For…

Differential Geometry · Mathematics 2008-04-11 Andreas Cap

Two distinct projections of finite rank $m$ are adjacent if their difference is an operator of rank two or, equivalently, the intersection of their images is $(m-1)$-dimensional. We extend this adjacency relation on other conjugacy classes…

Combinatorics · Mathematics 2020-06-30 Mark Pankov , Krzysztof Petelczyc , Mariusz Zynel

In this paper we define the (edge-weighted) Cayley graph associated to a generalized Boolean function, introduce a notion of strong regularity and give several of its properties. We show some connections between this concept and generalized…

Information Theory · Computer Science 2018-06-21 Constanza Riera , Pantelimon Stanica , Sugata Gangopadhyay

A biased graph is a graph $G$, together with a distinguished subset $\mathcal{B}$ of its cycles so that no Theta-subgraph of $G$ contains precisely two cycles in $\mathcal{B}$. A large number of biased graphs can be constructed by choosing…

Combinatorics · Mathematics 2020-12-14 Peter Nelson , Jorn van der Pol