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We introduce the notion of the Fourier and Fouier-Stieltjes algebra of a topological *-semigroup and show that these are commutative Banach algebras. For a class of foundation semigroups, we show that these are preduals of von Neumann…

Operator Algebras · Mathematics 2007-05-23 Massoud Amini , Alireza Medghalchi

Several classes of *-algebras associated to the action of an affine transformation are considered, and an investigation of the interplay between the different classes of algebras is initiated. Connections are established that relate…

Mathematical Physics · Physics 2009-03-16 Joakim Arnlind , Sergei Silvestrov

We study the outer automorphism group of a right-angled Artin group $A_\Gamma$ with finite defining graph $\Gamma$. We construct a subnormal series for $Out(A_\Gamma)$ such that each consecutive quotient is either finite, free-abelian,…

Group Theory · Mathematics 2019-04-24 Matthew B. Day , Richard D. Wade

The theory of Nichols algebras of diagonal type is known to be closely related to that of semisimple Lie algebras. In this paper the connection between both theories is made closer. For any Nichols algebra of diagonal type invertible…

Quantum Algebra · Mathematics 2016-09-07 I. Heckenberger

We consider Frobenius algebras in the monoidal category of right comodules over a Hopf algebra $H$. If $H$ is a group Hopf algebra, we study a more general Frobenius type property and uncover the structure of graded Frobenius algebras.…

Quantum Algebra · Mathematics 2013-07-30 Sorin Dascalescu , Constantin Nastasescu , Laura Nastasescu

In this paper we introduce new affine algebraic varieties whose points correspond to associative algebras. We show that the algebras within a variety share many important homological properties. In particular, any two algebras in the same…

Representation Theory · Mathematics 2019-11-13 Edward L. Green , Lutz Hille , Sibylle Schroll

We introduce and study elementary properties of graph homology of algebras. This new homology theory shares many features of cyclic and Hochschild homology. We also define a graph K-theory together with an analog of Chern character.

K-Theory and Homology · Mathematics 2007-05-23 M. V. Movshev

A groupoid that satisfies the left invertive law: $ab\cdot c=cb\cdot a$ is called an AG-groupoid. We extend the concept of left abelian distributive groupoid (LAD) and right abelian distributive groupoid (RAD) to introduce new subclasses of…

Group Theory · Mathematics 2014-03-21 Muhammad Rashad , Imtiaz Ahmad , Muhammad Shah

A Vogan diagram is a Dynkin diagram with a Cartan involution of twisted affine superlagebras based on maximally compact Cartan subalgebras. This article construct the Vogan diagrams of twisted affine superalgebras. It is a part of…

Mathematical Physics · Physics 2013-03-04 Biswajit Ransingh

Every countable directed graph generates a Fock space Hilbert space and a family of partial isometries. These operators also arise from the left regular representations of free semigroupoids derived from directed graphs. We develop a…

Operator Algebras · Mathematics 2007-05-23 David W. Kribs , Stephen C. Power

An AF-algebra is assigned to each cusp form f of weight two; we study properties of this operator algebra, when f is a Hecke eigenform.

Number Theory · Mathematics 2012-01-19 Igor Nikolaev

We define an admissible decomposition of a graph $E$ into subgraphs $F_1$ and $F_2$, and consider the intersection graph $F_1\cap F_2$ as a subgraph of both $F_1$ and $F_2$. We prove that, if the graph $E$ is row finite and its…

Operator Algebras · Mathematics 2019-06-04 Piotr M. Hajac , Sarah Reznikoff , Mariusz Tobolski

We define the notion of a twisted topological graph algebra associated to a topological graph and a $1$-cocycle on its edge set. We prove a stronger version of a Vasselli's result. We expand Katsura's results to study twisted topological…

Operator Algebras · Mathematics 2019-02-20 Hui Li

We calculate the ordered K_0-group of a graph C*-algebra and mention applications of this result to AF-algebras, states on the K_0-group of a graph algebra, and tracial states of graph algebras.

Operator Algebras · Mathematics 2007-05-23 Mark Tomforde

This dissertation concerns the classification of groupoid and higher-rank graph C*-algebras and has two main components. Firstly, for a groupoid it is shown that the notions of strength of convergence in the orbit space and…

Operator Algebras · Mathematics 2013-05-28 Robert Hazlewood

We investigate a construction which associates a finite von Neumann algebra $M(\Gamma,\mu)$ to a finite weighted graph $(\Gamma,\mu)$. Pleasantly, but not surprisingly, the von Neumann algebra associated to to a `flower with $n$ petals' is…

Operator Algebras · Mathematics 2011-02-23 Madhushree Basu , Vijay Kodiyalam , V. S. Sunder

A graph associahedron is a simple polytope whose face lattice encodes the nested structure of the connected subgraphs of a given graph. In this paper, we study certain graph properties of the 1-skeleta of graph associahedra, such as their…

Combinatorics · Mathematics 2017-12-15 Thibault Manneville , Vincent Pilaud

Consider a normal projective variety $X$, a linear algebraic subgroup $G$ of Aut($X$), and the field $K$ of $G$-invariant rational functions on $X$. We show that the subgroup of Aut($X$) that fixes $K$ pointwise is linear algebraic. If $K$…

Algebraic Geometry · Mathematics 2020-08-06 Michel Brion

Let G be a group and let W be an algebra over a field K. We will say that W is a G-graded twisted algebra if W can be written as a direct sum over the elements of G of one dimensional K-vector spaces. It is also assumed that W has no…

Rings and Algebras · Mathematics 2015-05-18 Juan P. Hernandez , Juan D. Velez , Luis A. Wills-Toro , Edisson Gallego

An algebraic domain is a closed topological subsurface of a real affine plane whose boundary consists of disjoint smooth connected components of real algebraic plane curves. We study the geometric shape of an algebraic domain by collapsing…

Geometric Topology · Mathematics 2023-06-09 Arnaud Bodin , Patrick Popescu-Pampu , Miruna-Stefana Sorea