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A contractive $n$-tuple $A=(A_1,...,A_n)$ has a minimal joint isometric dilation $S=(S_1,...,S_n)$ where the $S_i$'s are isometries with pairwise orthogonal ranges. This determines a representation of the Cuntz-Toeplitz algebra. When $A$…

Operator Algebras · Mathematics 2007-05-23 Kenneth R. Davidson , David W. Kribs , Miron E. Shpigel

We consider a bipartite distance-regular graph $G$ with diameter at least 4 and valency at least 3. Fix a vertex of $G$ and let $T$ denote the corresponding subconstituent algebra. We give a detailed description of a certain type of…

Combinatorics · Mathematics 2007-05-23 Mark MacLean , Paul Terwilliger

An anti-associative algebra is a nonassociative algebra whose multiplication satisfies the identity a(bc)+(ab)c=0. Such algebras are nilpotent. We describe the free anti-associative algebras with a finite number of generators. Other types…

Rings and Algebras · Mathematics 2024-04-12 Elisabeth Remm

In this paper we study various rigidity aspects of the von Neumann algebra $L(\Gamma)$ where $\Gamma$ is a graph product group \cite{Gr90} whose underlying graph is a certain cycle of cliques and the vertex groups are the wreath-like…

Operator Algebras · Mathematics 2025-06-03 Ionut Chifan , Michael Davis , Daniel Drimbe

We show that if two tensor algebras of topological graphs are algebraically isomorphic, then the graphs are locally conjugate. Conversely, if the base space is at most one dimensional and the edge space is compact, then locally conjugate…

Operator Algebras · Mathematics 2010-04-06 Kenneth R. Davidson , Jean Roydor

We study the structure of the generator of a symmetric, conservative quantum dynamical semigroup with norm-bounded generator on a von Neumann algebra equipped with a faithful semifinite trace. For von Neumann algebras with abelian commutant…

Mathematical Physics · Physics 2007-05-23 Sergio Albeverio , Debashish Goswami

We study the categorical-algebraic condition that internal actions are weakly representable (WRA) in the context of varieties of (non-associative) algebras over a field. Our first aim is to give a complete characterization of action…

Category Theory · Mathematics 2025-02-24 Jose Brox , Xabier García-Martínez , Manuel Mancini , Tim Van der Linden , Corentin Vienne

We analyze the decomposition of the enveloping algebra of the conformal algebra in arbitrary dimension with respect to the mass-squared operator. It emerges that the subalgebra that commutes with the mass-squared is generated by its…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Dana Mihai , George A. J. Sparling

Consider a compact locally symmetric space $M$ of rank $r$, with fundamental group $\Gamma$. The von Neumann algebra $\vn(\Gamma)$ is the convolution algebra of functions $f\in\ell_2(\Gamma)$ which act by left convolution on…

Operator Algebras · Mathematics 2013-02-25 Guyan Robertson

Let $\Gamma$ be a discrete group acting on a compact Hausdorff space $X$. Given $x\in X$, and $\mu\in\text{Prob}(X)$, we introduce the notion of contraction of $\mu$ towards $x$ with respect to unitary elements of a group von Neumann…

Operator Algebras · Mathematics 2024-10-09 Tattwamasi Amrutam , Jacopo Bassi

We describe a procedure to attach a nilpotent strong homotopy Lie algebra to every simple hypergraph and prove that two hypergraphs are isomorphic if and only if the corresponding strong homotopy Lie algebras are isomorphic. As an…

Combinatorics · Mathematics 2024-02-23 Marco Aldi , Samuel Bevins

In this article we study higher homological properties of $n$-levelled algebras and connect them to properties of the underlying graphs. Notably, to each $2$-representation-finite quadratic monomial algebra $\Lambda$ we associate a…

Representation Theory · Mathematics 2024-11-04 Karin M. Jacobsen , Mads Hustad Sandøy , Laertis Vaso

The Weisfeiler-Leman procedure is a widely-used technique for graph isomorphism testing that works by iteratively computing an isomorphism-invariant coloring of vertex tuples. Meanwhile, a fundamental tool in structural graph theory, which…

Discrete Mathematics · Computer Science 2022-07-19 Sandra Kiefer , Daniel Neuen

von Neumann algebras have been playing an increasingly important role in the context of gauge theories and gravity. The crossed product presents a natural method for implementing constraints through the commutation theorem, rendering it a…

High Energy Physics - Theory · Physics 2025-02-10 Shadi Ali Ahmad , Marc S. Klinger , Simon Lin

In \cite{CDD22} we investigated the structure of $\ast$-isomorphisms between von Neumann algebras $L(\Gamma)$ associated with graph product groups $\Gamma$ of flower-shaped graphs and property (T) wreath-like product vertex groups as in…

Operator Algebras · Mathematics 2025-06-03 Ionut Chifan , Michael Davis , Daniel Drimbe

Suppose F is a finite set of selfadjoint elements in a tracial von Neumann algebra M. For $\alpha >0$, F is $\alpha$-bounded if the free packing $\alpha$-entropy of F is bounded from above. We say that M is strongly 1-bounded if M has a…

Operator Algebras · Mathematics 2007-05-23 Kenley Jung

The parabolic algebra A_p is the weakly closed algebra on L^2(R) generated by the unitary semigroup of right translations and the unitary semigroup of multiplication by the analytic exponential functions e^{i\lambda x}, \lambda \geq 0. This…

Operator Algebras · Mathematics 2020-06-02 Eleftherios Kastis , Stephen Power

The principal observation of the present paper is that an inner isotopy (i.e. a principal isotopy defined by an algebra endomorphism) is a very helpful instrument in constructing and studying interesting classes of nonassociative algebras.…

Rings and Algebras · Mathematics 2024-09-11 Vladimir G. Tkachev

Given any simple biorientable graph it is shown that there exists a weak {*}-Hopf algebra constructed on the vector space of graded endomorphisms of essential paths on the graph. This construction is based on a direct sum decomposition of…

Quantum Algebra · Mathematics 2015-03-17 R. Trinchero

We describe an approach to classify (meromorphic) representations of a given vertex operator algebra by calculating Zhu's algebra explicitly. We demonstrate this for FKS lattice theories and subtheories corresponding to the Z_2 reflection…

High Energy Physics - Theory · Physics 2007-05-23 Klaus Lucke