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We show that the modular branching rule (in the sense of Harish-Chandra) on unipotent modules for finite unitary groups is piecewise described by particular connected components of the crystal graph of well-chosen Fock spaces, under…

Representation Theory · Mathematics 2015-02-09 Thomas Gerber , Gerhard Hiss

We give necessary and sufficient conditions for the functor that forgets the $(C, \gamma)$-coaction to be separable. This leads to a generalized notion of integrals. Finally, the applications of our results are considered.

Rings and Algebras · Mathematics 2015-01-13 Shuangjian Guo , Xiaohui Zhang

A commutative ring is said to have ITI with respect to an ideal a if the a-torsion functor preserves injectivity of modules. Classes of rings with ITI or without ITI with respect to certain sets of ideals are identified. Behaviour of ITI…

Commutative Algebra · Mathematics 2016-10-13 Pham Hung Quy , Fred Rohrer

We develop the homotopy theory of semisimplicial sets constructively and without reference to point-set topology to obtain a constructive model for $\omega$-groupoids. Most of the development is folklore, but for a few results the author is…

Category Theory · Mathematics 2018-10-01 Christian Sattler

We introduce a strategy to study irreducible representations of automorphism groups of finite modules over local rings. We prove that these automorphism groups fit in a hierarchy that facilitates a stratification of their irreducible…

Representation Theory · Mathematics 2024-11-26 Tyrone Crisp , Ehud Meir , Uri Onn

Let G be an unramified reductive group over a non archimedian local field F. The so-called "Langlands Fundamental Lemma" is a family of conjectural identities between orbital integrals for G(F) and orbital integrals for endoscopic groups of…

Algebraic Geometry · Mathematics 2007-05-23 G. Laumon , B. C. Ngo

In their work on differential operators in positive characteristic, Smith and Van den Bergh define and study the derived functors of differential operators; they arise naturally as obstructions to differential operators reducing to positive…

Commutative Algebra · Mathematics 2018-12-10 Jack Jeffries

We develop the theory of groupoid graded semisimple rings. Our rings are neither unital nor one-sided artinian. Instead, they exhibit a strong version of having local units and being locally artinian, and we call them $\Gamma_0$-artinian.…

Rings and Algebras · Mathematics 2025-12-16 Zaqueu Cristiano , Wellington Marques de Souza , Javier Sánchez

We give in this paper an isomorphism theorem between derived functors over categories of modules.There is a nice class of categories that gives examples in which this theorem applies for a special construction. This leads us to a new…

Algebraic Topology · Mathematics 2007-05-23 Mathieu Zimmermann

Suppose we are given complex manifolds $X$ and $Y$ together with substacks $\mathcal{S}$ and $\mathcal{S}'$ of modules over algebras of formal deformation $\mathcal{A}$ on $X$ and $\mathcal{A}'$ on $Y$, respectively. Suppose also we are…

Algebraic Geometry · Mathematics 2013-01-10 Ana Rita Martins , Teresa Monteiro Fernandes , David Raimundo

We obtain Fuchs decomposition theorem for regular singular differential modules over a large class of differential rings. We provide a definition of regularity inspired by differential Galois theory and we deduce the classical equivalence…

Number Theory · Mathematics 2024-11-27 Andrea Pulita

Since for the classification of finite (congruence-)simple semirings it remains to classify the additively idempotent semirings, we progress on the characterization of finite simple additively idempotent semirings as semirings of…

Rings and Algebras · Mathematics 2013-01-01 Andreas Kendziorra , Jens Zumbrägel

Functorial semi-norms are semi-normed refinements of functors such as singular (co)homology. We investigate how different types of representability affect the (non-)triviality of finite functorial semi-norms on certain functors or classes.…

Algebraic Topology · Mathematics 2015-09-08 Clara Loeh

Using approximations, we give several characterizations of separability of bimodules. We also discuss how separability properties can be used to transfer some representation theoretic properties from one ring to another one: contravariant…

Rings and Algebras · Mathematics 2007-05-23 S. Caenepeel , Bin Zhu

Several authors have introduced various type of coherent-like rings and proved analogous results on these rings. It appears that all these relative coherent rings and all the used techniques can be unified. In [2], several coherent-like…

Commutative Algebra · Mathematics 2020-09-01 Mostafa Amini , Arij Benkhadra , Bennis , Mohammed Hajoui

We determine necessary and sufficient conditions on the ring of differential operators of a finite purely inseparable field extension of positive characteristic for determining whether the extension is modular.

Commutative Algebra · Mathematics 2013-12-03 Matt Wechter

We prove trace and extension results for Sobolev-type function spaces that are well suited for nonlocal Dirichlet and Neumann problems including those for the fractional $p$-Laplacian. Our results are robust with respect to the order of…

Analysis of PDEs · Mathematics 2025-11-12 Florian Grube , Moritz Kassmann

We give a new purely algebraic approach to odd unitary groups using odd form rings. Using these objects, we prove the stability theorems for odd unitary $K_1$-functor without using the corresponding result from linear $K$-theory under the…

Group Theory · Mathematics 2020-12-23 Egor Voronetsky

Let $R$ be a commutative noetherian ring. The $n$-semidualizing modules of $R$ are generalizations of its semidualizing modules. We will prove some basic properties of $n$-semidualizing modules. Our main result and example shows that the…

Commutative Algebra · Mathematics 2022-10-04 Tony Se

We use the theory of group actions on profinite trees to prove that the fundamental group of a finite, 1-acylindrical graph of free groups with finitely generated edge groups is conjugacy separable. This has several applications: we prove…

Group Theory · Mathematics 2009-06-02 Owen Cotton-Barratt , Henry Wilton