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We use the concept of a regular object with respect to another object in an arbitrary category, defined in \cite{dntd}, in order to obtain the transfer of regularity in the sense of Zelmanowitz between the categories $R-$mod and $S-$mod,…

Rings and Algebras · Mathematics 2008-03-11 Leonard Daus

We revisit the modular flavor symmetry from a more general perspective. The scalar modular forms of principal congruence subgroups are extended to the vector-valued modular forms, then we have more possible finite modular groups including…

High Energy Physics - Phenomenology · Physics 2022-04-13 Xiang-Gan Liu , Gui-Jun Ding

Let G be a connected reductive group, P its parabolic subgroup. We consider the parabolic semi-infinite category of sheaves on the affine Grassmanian of G and construct the parabolic version of the semi-infinite IC-sheaf of each orbit. We…

Representation Theory · Mathematics 2025-07-08 G. Dhillon , S. Lysenko

We define an extension of the affine Brauer algebra, the type B/C affine Brauer algebra. This new algebra contains the hyperoctahedral group and it naturally acts on $END_K(X \otimes V^{\otimes k})$ for Orthogonal and Symplectic groups.…

Representation Theory · Mathematics 2020-02-17 Kieran Calvert

Let $LG$ be the loop group of a compact, connected Lie group $G$. We show that the tangent bundle of any proper Hamiltonian $LG$-space $\mathcal{M}$ has a natural completion $\overline{T}\mathcal{M}$ to a strongly symplectic…

Symplectic Geometry · Mathematics 2017-06-26 Yiannis Loizides , Eckhard Meinrenken , Yanli Song

Using computations in the bidual of $\mathbb{B}(L^2M)$ we develop a new technique at the von Neumann algebra level to upgrade relative proper proximality to full proper proximality. This is used to structurally classify subalgebras of…

Operator Algebras · Mathematics 2023-08-04 Changying Ding , Srivatsav Kunnawalkam Elayavalli

We establish a bijection between torsion pairs in the category of finite-dimensional modules over a finite-dimensional algebra A and pairs (Z, I) formed by a closed rigid set Z in the Ziegler spectrum of A and a set I of indecomposable…

Representation Theory · Mathematics 2024-03-04 Lidia Angeleri Hügel , Rosanna Laking , Francesco Sentieri

This is the second of two papers but has been written so as to have minimal dependence on the first paper (which is also on this archive). Let G be a group and let M be a CAT(0) proper metric space (e.g. a simply connected complete…

Group Theory · Mathematics 2007-05-23 Robert Bieri , Ross Geoghegan

We augment the body of existing results on embedding finite semigroups of a certain type into 2-generator finite semigroups of the same type. The approach adopted applies to finite semigroups the idempotents of which form a band and also to…

Group Theory · Mathematics 2019-01-25 Peter M. Higgins

We study Lie algebroids in positive characteristic and moduli spaces of their modules. In particular, we show a Langton's type theorem for the corresponding moduli spaces. We relate Langton's construction to Simpson's construction of…

Algebraic Geometry · Mathematics 2015-03-24 Adrian Langer

We construct a new set of combinations from the mass matrices of the charged leptons and neutrinos that are invariant under basis transformation, hereafter {\it the} invariants. We use these invariants to study various symmetries and…

High Energy Physics - Phenomenology · Physics 2009-02-02 Arman Esmaili , Yasaman Farzan

Consider a finite-dimensional algebra $A$ and any of its moduli spaces $\mathcal{M}(A,\mathbf{d})^{ss}_{\theta}$ of representations. We prove a decomposition theorem which relates any irreducible component of…

Representation Theory · Mathematics 2018-09-25 Calin Chindris , Ryan Kinser

We study the closures of subgroups, semilattices and different kinds of semigroup extensions in semitopological inverse semigroups with continuous inversion. In particularly we show that a topological group $G$ is $H$-closed in the class of…

Group Theory · Mathematics 2014-10-07 Oleg Gutik

We classify (up to quasi-isomorphism) the free differential modules whose homology is equal to a given module $M$ by developing a theory for deforming an arbitrary free complex into a differential module. We use an iterative approach to…

Commutative Algebra · Mathematics 2023-08-07 Maya Banks , Keller VandeBogert

In this paper we use A-infinity modules to study the derived category of a finite dimensional algebra over an algebraically closed field. We study varieties parameterising A-infinity modules. These varieties carry an action of an algebraic…

Representation Theory · Mathematics 2007-05-29 Bernt Tore Jensen , Dag Madsen , Xiuping Su

It was observed recently that for a fixed finite group $G$, the set of all Drinfeld centres of $G$ twisted by 3-cocycles form a group, the so-called group of modular extensions (of the representation category of $G$), which is isomorphic to…

Category Theory · Mathematics 2018-06-05 Alexei Davydov , Darren Simmons

We complete the classical and modern work on the classification of conjugacy classes of finite subgroups of the group of birational transformations of the complex projective plane.

Algebraic Geometry · Mathematics 2009-04-13 Igor V. Dolgachev , Vasily A. Iskovskikh

We generalize the modular invariance approach to include the half-integral weight modular forms. Accordingly the modular group should be extended to its metaplectic covering group for consistency. We introduce the well-defined half-integral…

High Energy Physics - Phenomenology · Physics 2021-01-04 Xiang-Gan Liu , Chang-Yuan Yao , Bu-Yao Qu , Gui-Jun Ding

We study Mittag-Leffler conditions on modules providing relative versions of classical results by Raynaud and Gruson. We then apply our investigations to several contexts. First of all, we give a new argument for solving the Baer splitting…

Rings and Algebras · Mathematics 2007-05-23 Lidia Angeleri-Hugel , Dolors Herbera

We introduce a new type of reduction of inversive difference polynomials that is associated with a partition of the basic set of automorphisms $\sigma$ and uses a generalization of the concept of effective order of a difference polynomial.…

Rings and Algebras · Mathematics 2023-09-12 Alexander Levin