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We provide necessary and/or sufficient conditions for the stable Hom functors to be finitely presented. When the covariant Hom functor modulo projectives is finitely presented, its defect is isomorphic to the Bass torsion of the fixed…

Category Theory · Mathematics 2024-03-21 Alex Martsinkovsky

Quasi-projective dimension of modules over associative rings is generalized in this paper to the one of complexes of modules. Basic properties of this dimension are established, including a comparison result with projective dimension and a…

Rings and Algebras · Mathematics 2026-04-13 Hongxing Chen , Jiangsheng Hu , Xiaoyan Yang

Many rings and algebras arising in quantum mechanics, algebraic analysis, and non-commutative algebraic geometry can be interpreted as skew PBW (Poincar\'e-Birkhoff-Witt) extensions. In the present paper we study two aspects of these…

Rings and Algebras · Mathematics 2015-10-13 Oswaldo Lezama , Claudia Gallego

Motivated by Arveson's conjecture, we introduce a notion of hyperrigidity for a partial order on the state space of a $C^*$-algebra $B$. We show how this property is equivalent to the existence of a boundary: a subset of the pure states…

Operator Algebras · Mathematics 2023-10-27 Raphaël Clouâtre , Hridoyananda Saikia

A famous conjecture attributed to Kodaira asks whether any compact Kaehler manifold can be approximated by projective manifolds. We confirm this conjecture on projectivized direct sums of three line bundles on three-dimensional complex tori…

Algebraic Geometry · Mathematics 2007-05-23 Jean-Pierre Demailly , Thomas Eckl , Thomas Peternell

We study open equivariant projective embeddings of homogeneous spaces such that the complement of the open orbit does not contain divisors. Criterions of existence of such an embedding are considered and finiteness of isomorphism classes of…

Algebraic Geometry · Mathematics 2015-05-13 Ivan V. Arzhantsev

In this paper we consider a gauge action on sigma model solitons over noncommutative tori as source spaces, with a target space made of two points introduced in \cite{DKL:Sigma}. Using new classes of solitons from Gabor frames, we quantify…

Operator Algebras · Mathematics 2018-02-06 Hyun Ho Lee

Gheibi, Jorgensen and Takahashi recently introduced the quasi-projective dimension of a module over commutative Noetherian rings, a homological invariant extending the classic projective dimension of a module, and Gheibi later developed the…

Commutative Algebra · Mathematics 2025-11-07 Souvik Dey , Luigi Ferraro , Mohsen Gheibi

The relationship between convex geometry and algebraic geometry has deep historical roots, tracing back to classical works in enumerative geometry. In this paper, we continue this theme by studying two interconnected problems regarding…

Algebraic Geometry · Mathematics 2025-06-17 Daoji Huang , June Huh , Mateusz Michałek , Botong Wang , Shouda Wang

We consider the set of pairs of orthogonal vectors in Hilbert space, which is also called the cross because it is the union of the horizontal and vertical axes in the Euclidean plane when the underlying space is the real line. Crosses,…

Optimization and Control · Mathematics 2022-02-04 Heinz H. Bauschke , Manish Krishan Lal , Xianfu Wang

Given a Hopf algebra H, we study modules and bimodules over an algebra A that carry an H-action, as well as their morphisms and connections. Bimodules naturally arise when considering noncommutative analogues of tensor bundles. For…

Quantum Algebra · Mathematics 2014-11-10 Paolo Aschieri , Alexander Schenkel

Let $T$ be a tilting module. In this paper, Gorenstein $\pi[T]$-projective modules are introduced and some of their basic properties are studied. Moreover, some characterizations of rings over which all modules are Gorenstein…

Commutative Algebra · Mathematics 2019-03-19 M. Amini

Let $T_R(M)$ be a tensor ring and $\mathcal{X}$, $\mathcal{Y}$ be two classes of $R$-modules. Under certain conditions, we prove that a $T_R(M)$-module $(A, u)$ is $Ind(\mathcal{X})$-Gorenstein projective if and only if $u$ is monomorphic…

Rings and Algebras · Mathematics 2025-12-30 Guoqiang Zhao , Juxiang Sun

Ordinary theta-functions can be considered as holomorphic sections of line bundles over tori. We show that one can define generalized theta-functions as holomorphic elements of projective modules over noncommutative tori (theta-vectors).…

Quantum Algebra · Mathematics 2007-05-23 Albert Schwarz

In this paper, we first study the Gorenstein projective/flat dimension of complexes of modules. The relation between the Gorenstein projective/flat dimension for complexes and that for modules are investigated. Then we study Tate, stable…

Rings and Algebras · Mathematics 2020-09-18 Li Liang

We study aspects of gauge theory on tori which are a consequences of Morita equivalence. In particular we study the behavior of gauge theory on noncommutative tori for arbitrarily close rational values of Theta. For such values of Theta,…

High Energy Physics - Theory · Physics 2010-02-03 Zachary Guralnik , Jan Troost

We consider converses to the density theorem for irreducible, projective, unitary group representations restricted to lattices using the dimension theory of Hilbert modules over twisted group von Neumann algebras. We show that under the…

Operator Algebras · Mathematics 2022-10-21 Ulrik Enstad

Weighted Rota-Baxter Jacobi-Jordan algebras and their representations are studied. Moreover, we consider weighted Rota-Baxter paired operators that are related to weighted Rota-Baxter Jacobi-Jordan algebras together with their…

Rings and Algebras · Mathematics 2025-08-14 Jules Anitchéou , Sylvain Attan

In this note, we investigate the Baer splitting problem over commutative rings. In particular, we show that if a commutative ring $R$ is $\tau_q$-semisimple, then every Baer $R$-module is projective.

Commutative Algebra · Mathematics 2025-09-05 Xiaolei Zhang , Hwankoo Kim

We make use of the concepts of Tor-rigid and rigid-test modules, among others, to investigate the interplay between cohomology vanishing and the finiteness of several homological dimensions such as projective, injective and Gorenstein…

Commutative Algebra · Mathematics 2022-12-22 Victor H. Jorge-Pérez , Cleto B. Miranda-Neto