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We investigate the structure of crossed product von Neumann algebras arising from Bogoljubov actions of countable groups on Shlyakhtenko's free Araki-Woods factors. Among other results, we settle the questions of factoriality and Connes'…

Operator Algebras · Mathematics 2025-07-17 Cyril Houdayer , Benjamin Trom

Let $\mathbb{N} \mathcal{A}$ be the monoid generated by $\mathcal{A} = {\mathbf{a}_1, ..., \mathbf{a}_n} \subseteq \mathbb{Z}^d.$ We introduce the homogeneous catenary degree of $\mathbb{N} \mathcal{A}$ as the smallest $N \in \mathbb N$…

Commutative Algebra · Mathematics 2013-10-09 Pedro A. García-Sánchez , Ignacio Ojeda , Alfredo Sánchez-R. -Navarro

As shown by S. Eilenberg and J.C. Moore (1965), for a monad $F$ with right adjoint comonad $G$ on any catgeory $\mathbb{A}$, the category of unital $F$-modules $\mathbb{A}_F$ is isomorphic to the category of counital $G$-comodules…

Category Theory · Mathematics 2015-12-14 Wisbauer Robert

Inspired by the results of [R. Adin, A. Postnikov, Y. Roichman, Combinatorial Gelfand model, preprint math.RT arXiv:0709.3962], we propose combinatorial Gelfand models for semigroup algebras of some finite semigroups, which include the…

Representation Theory · Mathematics 2010-04-02 Ganna Kudryavtseva , Volodymyr Mazorchuk

Firstly, precise conditions on how to obtain very-well-behaved epireflections are explored and improved from the author's previous papers; meaning that, beginning with a monad and a prefactorization system on a category, is produced a…

Category Theory · Mathematics 2025-09-10 João J. Xarez

Given a finitely-generated group G, and a finite group \Gamma, Philip Hall defined \delta_\Gamma to be the number of factor groups of G that are isomorphic to \Gamma. We show how to compute the Hall invariants by cohomological and…

Group Theory · Mathematics 2007-05-23 Daniel Matei , Alexander I. Suciu

We apply the notion of a full convex subcategory to a wide range of algebras including tilted, quasi-tilted, shod, weakly shod, left and right glued, laura, simply connected, strongly simply connected, left supported, and cluster-tilted. In…

Representation Theory · Mathematics 2020-06-30 Stephen Zito

We present a homotopy theory for a weak version of modular operads whose compositions and contractions are only defined up to homotopy. This homotopy theory takes the form of a Quillen model structure on the collection of simplicial…

Algebraic Topology · Mathematics 2020-07-03 Philip Hackney , Marcy Robertson , Donald Yau

This work extends the results known for the Delta sets of non-symmetric numerical semigroups with embedding dimension three to the symmetric case. Thus, we have a fast algorithm to compute the Delta set of any embedding dimension three…

Commutative Algebra · Mathematics 2017-01-05 P. A. García-Sánchez , D. Llena , A. Moscariello

We relate the topology of the Morse boundary of a group to geometric and algorithmic properties of the group. In particular, we show that a group has $\sigma$-compact Morse boundary if and only if it is Morse local-to-global. We also…

Group Theory · Mathematics 2026-05-13 Carolyn Abbott , Stefanie Zbinden

We develop a numerically exact method for the summation of irreducible Feynman diagrams for fermionic self-energy in the thermodynamic limit. The technique, based on the Diagrammatic Determinant Monte Carlo and its recent extension to…

Strongly Correlated Electrons · Physics 2019-09-11 Fedor Simkovic IV. , Evgeny Kozik

For any category ${\mathcal E}$ and monad $T$ thereon, we introduce the notion of $T$-simplicial object in ${\mathcal E}$. Any $T$-category in the sense of Burroni induces a $T$-simplicial object as its nerve. This nerve construction…

Category Theory · Mathematics 2026-03-13 Soichiro Fujii , Stephen Lack

In this paper, we present a new class of strongly singular maximal abelian subalgebras living inside the k-folded tensor product of the free group factor (on N>1 generators). A. Sinclair and R. Smith introduced the class of strongly…

Operator Algebras · Mathematics 2007-05-23 Teodor Stefan Bildea

Let $\mathbb{k}$ be a characteristic zero domain. For a locally unital $\mathbb{k}$-superalgebra $A$ with distinguished idempotents $I$and even subalgebra $a \subseteq A_{\bar 0}$, we define and study an associated diagrammatic monoidal…

Representation Theory · Mathematics 2023-02-09 Nicholas Davidson , Jonathan R. Kujawa , Robert Muth , Jieru Zhu

We present our position on the elusive quest for a general-purpose framework for specifying and studying deep learning architectures. Our opinion is that the key attempts made so far lack a coherent bridge between specifying constraints…

Machine Learning · Computer Science 2024-06-07 Bruno Gavranović , Paul Lessard , Andrew Dudzik , Tamara von Glehn , João G. M. Araújo , Petar Veličković

In 1983, Feingold and Frenkel discovered a relation between Siegel modular forms of genus two and a rank-three hyperbolic Kac--Moody algebra extending the affine Lie algebra of type $A_1$. It inspires a problem to explore more general…

Number Theory · Mathematics 2025-07-08 Kaiwen Sun , Haowu Wang , Brandon Williams

We develop the Morita theory of fusion 2-categories. In order to do so, we begin by proving that the relative tensor product of modules over a separable algebra in a fusion 2-category exists. We use this result to construct the Morita…

Category Theory · Mathematics 2023-06-06 Thibault D. Décoppet

Let $G$ be a group acting properly by isometries and with a strongly contracting element on a geodesic metric space. Let $N$ be an infinite normal subgroup of $G$, and let $\delta_N$ and $\delta_G$ be the growth rates of $N$ and $G$ with…

Group Theory · Mathematics 2020-06-10 Goulnara N. Arzhantseva , Christopher H. Cashen

Let G be a discrete, torsion free group with a finite dimensional classifying space BG. We show that the existence of a gamma-element for such G is a metric, that is, coarse, invariant of G. We also obtain results for groups with torsion.…

K-Theory and Homology · Mathematics 2007-05-23 Heath Emerson , Ralf Meyer

In this article, we apply the derived Morita theory of dg-categories to show how to extend the domain of validity of many identities relating Morita invariants from associative dg-algebras toward non-commutative scheme. Doing so, we obtain…

Algebraic Geometry · Mathematics 2024-12-13 Alexandre Nicolle