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We characterize projective and injective Banach modules in approximate terms, generalizing thereby a characterization of contractible Banach algebras given by F. Ghahramani and R. J. Loy. As a corollary, we show that each uniformly…

Functional Analysis · Mathematics 2019-05-01 A. Yu. Pirkovskii

Recently, several authors have adopted new alternative approaches in the study of some classical notions of modules. Among them, we find the notion of subprojectivity which was introduced to measure in a way the degree of projectivity of…

Rings and Algebras · Mathematics 2021-06-22 Driss Bennis , J. R. Garcia Rozas , Hanane Ouberka , Luis Oyonarte

Let $G$ be a locally compact group. In this paper, we study various invariant subspaces of the duals of the algebras $A_M(G)$ and $A_{cb}(G)$ obtained by taking the closure of the Fourier algebra $A(G)$ in the multiplier algebra $MA(G)$ and…

Functional Analysis · Mathematics 2023-04-14 Brian Forrest , John Sawatzky , Aasaimani Thamizhazhagan

Over the past three decades, there have been several attempts to characterize modules over affine Lie superalgebras. One of the main issues in this regard is dealing with zero-level modules. In this paper, we study these modules and…

Representation Theory · Mathematics 2026-01-30 Malihe Yousofzadeh

Let L(n-l+1/2,0) be the vertex operator algebra associated to an affine Lie algebra of type B_l^(1) at level n-l+1/2, for a positive integer n. We classify irreducible L(n-l+1/2,0)-modules and show that every L(n-l+1/2,0)-module is…

Quantum Algebra · Mathematics 2010-06-10 Ozren Perse

We extend Langton's valuative criterion for families of coherent algebraic sheaves to a complex analytic set-up. As a consequence we derive a set of sufficient conditions for the compactness of a moduli space of semistable sheaves over a…

Algebraic Geometry · Mathematics 2021-08-30 Matei Toma

Projective structures on topological surfaces support the structure of 2d CFTs with a degree of technical simplification. We propose a complex analytic space $\mathcal{P}_g$ biholomorphic to $T^*_{(1,0)} \mathcal{M}_g$ as a candidate moduli…

High Energy Physics - Theory · Physics 2024-11-05 Xiao Liu

We describe weighted projective lines in the sense of Geigle and Lenzing by a moduli problem on the canonical algebra of Ringel. We then go on to study generators of the derived categories of coherent sheaves on the total spaces of their…

Algebraic Geometry · Mathematics 2014-09-25 Tarig Abdelgadir , Kazushi Ueda

We investigate whether the group algebra of a finite group over a localisation of the integers is semiperfect. The main result is a necessary and sufficient arithmetic criterion in the ordinary case. In the modular case, we propose a…

Rings and Algebras · Mathematics 2025-10-10 Dylan Johnston , Dmitriy Rumynin

We study vertex algebras and their modules associated with possibly degenerate even lattices, using an approach somewhat different from others. Several known results are recovered and a number of new results are obtained. We also study…

Quantum Algebra · Mathematics 2008-02-04 Haisheng Li , Qing Wang

We show how natural functors from the category of coherent sheaves on a projective scheme to categories of Kronecker modules can be used to construct moduli spaces of semistable sheaves. This construction simplifies or clarifies technical…

Algebraic Geometry · Mathematics 2009-11-11 Luis Álvarez-Cónsul , Alastair King

Given a compact, metric space X, we show that the commutative C*-algebra C(X) is semiprojective if and only if X is an absolute neighborhood retract of dimension at most one. This confirms a conjecture of Blackadar. Generalizing to the…

Operator Algebras · Mathematics 2013-02-05 Adam P. W. Sørensen , Hannes Thiel

In this paper we study categories of tilting modules. Our starting point is the tilting modules for a reductive algebraic group G in positive characteristic. Here we extend the main result in [8] by proving that these tilting modules form a…

Representation Theory · Mathematics 2020-02-27 Henning Haahr Andersen

We show that if a locally compact group $G$ is non-abelian then the amenability constant of its Fourier algebra is $\geq 3/2$, extending a result of Johnson (JLMS, 1994) who proved that this holds for finite non-abelian groups. Our lower…

Functional Analysis · Mathematics 2023-11-22 Y. Choi

We investigate weight modules for finite and infinite Weyl algebras, classifying all such simple modules. We also study the representation type of the blocks of locally-finite weight module categories and describe indecomposable modules in…

Rings and Algebras · Mathematics 2007-05-23 Viktor Bekkert , Georgia Benkart , Vyacheslav Futorny

The Fourier and Fourier-Stieltjes algebras $A(G)$ and $B(G)$ of a locally compact group $G$ are introduced and studied in 60's by Piere Eymard in his PhD thesis. If $G$ is a locally compact abelian group, then $A(G)\simeq L^1(\hat{G})$, and…

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

In a former paper we introduced the concept of localisation of ideals in the Fourier algebra of a locally compact Abelian group. It turns out that localisability of a closed ideal in the Fourier algebra is equivalent to the synthesisability…

Functional Analysis · Mathematics 2023-08-22 László Székelyhidi

We show that a compact rigid balanced braided monoidal category with enough compact projective objects gives rise to a system of mapping class group representations compatible with the gluing along marked intervals. A motivation to consider…

Quantum Algebra · Mathematics 2026-02-24 Deniz Yeral

The notion of operator amenability was introduced by Z.-J. Ruan in 1995. He showed that a locally compact group G is amenable if and only if its Fourier algebra A(G) is operator amenable. In this paper, we investigate the operator…

Functional Analysis · Mathematics 2009-11-07 Volker Runde , Nico Spronk

We show that if A is an abelian category satisfying certain mild conditions, then one can introduce the concept of a moduli space of (semi)stable objects which has the structure of a projective algebraic variety. This idea is applied to…

Algebraic Geometry · Mathematics 2012-01-04 Vyacheslav Futorny , Marcos Jardim , Adriano Moura