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This paper contains a quite detailed description of the C*-algebra arising from the transformation groupoid of a rational map of degree at least two on the Riemann sphere. The algebra is decomposed stepwise via extensions of familiar…

Operator Algebras · Mathematics 2012-02-14 Klaus Thomsen

We define a class of morphisms between \'etale groupoids and show that there is a functor from the category with these morphisms to the category of $C^*$-algebras. We show that all homomorphisms between Cartan pairs of $C^*$-algebras that…

Operator Algebras · Mathematics 2023-11-03 Jonathan Taylor

We shall consider a locally compact groupoid endowed with a Haar system and having proper orbit space. We shall construct a groupoid C*-algebra which is independent of the Haar system (up to a *-isomorphism).

Operator Algebras · Mathematics 2007-05-23 Madalina Roxana Buneci

We demonstrate that graph-based models are fully capable of representing higher-order interactions, and have a long history of being used for precisely this purpose. This stands in contrast to a common claim in the recent literature on…

Physics and Society · Physics 2026-02-20 Tiago P. Peixoto , Leto Peel , Thilo Gross , Manlio De Domenico

The construction of a C*-algebra of a differential groupoid is presented. It is shown that it defines a covariant functor from the category of differential groupoids in a sense of S. Zakrzewski to the category of C*-algebras.

Quantum Algebra · Mathematics 2007-05-23 Piotr Stachura

We describe a construction by G\'abor Elek, associating C*-algebras with uniformly recurrent subgroups, in the language of groupoid C*-algebras. This allows us to simplify several proofs in the original paper and fully characterise their…

Operator Algebras · Mathematics 2019-08-06 Clemens Borys

Understanding the structure of a graph along with the structure of its subgraphs is important for several problems in graph theory. Two examples are the Reconstruction Conjecture and isomorph-free generation. This paper raises the question…

Combinatorics · Mathematics 2009-09-18 Stephen G. Hartke , Hannah Kolb , Jared Nishikawa , Derrick Stolee

$C_\infty$ Algebras and their morphisms are a framework in which one can study algebras and their maps that are not commutaive-associative but are homotopic to being that. In statistics cumulants measure the independence of random…

Algebraic Topology · Mathematics 2017-10-18 Nissim Ranade

Graphs are a useful abstraction of image content. Not only can graphs represent details about individual objects in a scene but they can capture the interactions between pairs of objects. We present a method for training a convolutional…

Computer Vision and Pattern Recognition · Computer Science 2018-03-28 Alejandro Newell , Jia Deng

Given an action of a groupoid by isomorphisms on a Fell bundle (over another groupoid), we form a semidirect-product Fell bundle, and prove that its $C^{*}$-algebra is isomorphic to a crossed product.

Operator Algebras · Mathematics 2021-12-30 Lucas Hall , S. Kaliszewski , John Quigg , Dana P. Williams

We undertake a study of the notion of a quantum graph over arbitrary finite-dimensional $C^*$-algebras $B$ equipped with arbitrary faithful states. Quantum graphs are realised principally as either certain operators on $L^2(B)$, the quantum…

Operator Algebras · Mathematics 2024-11-27 Matthew Daws

We introduce the notion of a topological higher-rank graph, a unified generalization of the higher-rank graph and the topological graph. Using groupoid techniques, we define the Toeplitz and Cuntz-Krieger algebras of topological higher-rank…

Operator Algebras · Mathematics 2007-05-23 Trent Yeend

We give a unified description of morphisms and comorphisms of Lie pseudoalgebras, showing that the both types of morphisms can be regarded as subalgebras of a Lie pseudoalgebra, called the $\psi$-sum. We also provide similar descriptions…

Rings and Algebras · Mathematics 2007-10-12 Z. Chen , Z. -J. Liu

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 formulate a notion of the quantum automorphism group of a $2$-graph. After some preliminary computations, we define quantum isomorphism between a pair of $2$-graphs. We produce a `non-trivial' example of a pair of $2$-graphs that are not…

Operator Algebras · Mathematics 2025-04-01 Soumalya Joardar , Atibur Rahaman , Jitender Sharma

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

A graph with a semiregular group of automorphisms can be thought of as the derived cover arising from a voltage graph. Since its inception, the theory of voltage graphs and their derived covers has been a powerful tool used in the study of…

Combinatorics · Mathematics 2019-10-21 Primoz Potocnik , Micael Toledo

In this paper, we extend the recently introduced concept of partially dual ribbon graphs to graphs. We then go on to characterize partial duality of graphs in terms of bijections between edge sets of corresponding graphs. This result…

Combinatorics · Mathematics 2012-03-01 Iain Moffatt

A description of group automorphisms of all two-dimensional algebras, considered up to isomorphism, over any basic field is provided.

Rings and Algebras · Mathematics 2024-11-19 Sh. Eshmirzayev , U. Bekbaev

k-graphs are higher-rank analogues of directed graphs which were first developed to provide combinatorial models for operator algebras of Cuntz-Krieger type. Here we develop the theory of covering spaces for k-graphs, obtaining a…

Operator Algebras · Mathematics 2008-05-23 David Pask , John Quigg , Iain Raeburn