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There is a forgetful functor from the category of generalized effect algebras to the category of effect algebras. We prove that this functor is a right adjoint and that the corresponding left adjoint is the well-known unitization…

Rings and Algebras · Mathematics 2017-03-28 Gejza Jenča

For an associative ring $R$, let $P$ be an $R$-module with $S=\End_R(P)$. C.\ Menini and A. Orsatti posed the question of when the related functor $\Hom_R(P,-)$ (with left adjoint $P\ot_S-$) induces an equivalence between a subcategory of…

Category Theory · Mathematics 2009-09-18 John Clark , Robert Wisbauer

We prove a variant of Emerton's conjecture concerning the right derived functors of the ordinary parts functor $\operatorname{Ord}_P^G$. This functor plays an important role in the theory of mod $p$ representations of $p$-adic reductive…

Representation Theory · Mathematics 2025-08-21 Manuel Hoff , Sarah Diana Meier , Michael Spieß , Claudius Heyer

We show that the left and right adjoint of the Schur functor can be expressed in terms of the monoidal structure of strict polynomial functors. Using this result we give a necessary and sufficient condition for when the tensor product of…

Representation Theory · Mathematics 2016-01-21 Rebecca Reischuk

We obtain Morita invariant versions of Eilenberg-Watts type theorems, relating Deligne products of finite linear categories to categories of left exact as well as of right exact functors. This makes it possible to switch between different…

Representation Theory · Mathematics 2019-11-15 Jürgen Fuchs , Gregor Schaumann , Christoph Schweigert

Given a Fourier-Mukai functor $\Phi$ in the general setting of singular schemes, under various hypotheses we provide both left and a right adjoints to $\Phi$, and also give explicit formulas for them. These formulas are simple and natural,…

Algebraic Geometry · Mathematics 2015-05-06 Alice Rizzardo

Given a right adjoint functor between triangulated categories and an object in the target category, we show that the unit map of adjunction on that object is a split monomorphism if and only if the object belongs to the additive closure of…

Algebraic Geometry · Mathematics 2024-05-13 Souvik Dey

We investigate functors between abelian categories having a left adjoint and a right adjoint that are \emph{similar} (these functors are called \emph{quasi-Frobenius functors}). We introduce the notion of a \emph{quasi-Frobenius bimodule}…

Rings and Algebras · Mathematics 2008-09-03 F. Castano Iglesias , C. Nastasescu , J. Vercruysse

In this paper we investigate the categories of braided objects, algebras and bialgebras in a given monoidal category, some pairs of adjoint functors between them and their relations. In particular we construct a braided primitive functor…

Category Theory · Mathematics 2013-04-15 Alessandro Ardizzoni , Claudia Menini

In this paper, we extend the notion of modular functor and fusion category to what we called $G$ equivariant modular functor and $G$ equivariant fusion category, where $G$ is a finite group, and establish a correspondence between between…

Quantum Algebra · Mathematics 2008-07-08 Alexander Kirillov , Tanvir Prince

In this work we state conditions on a covariant right exact functor so that it commutes with direct limits. These conditions are related to the commutativity of the functor under direct limits of projective modules. We prove that if the…

Category Theory · Mathematics 2023-11-16 R. García-Delgado

In this work, we investigate an effective method for showing that functors between categories are left adjoints. The method applies to a large class of categories, namely locally finitely presentable categories, which are ubiquitous in…

Category Theory · Mathematics 2025-01-28 Simon Forest

The setting is the representation theory of a simply connected, semisimple algebraic group over a field of positive characteristic. There is a natural transformation from the wall-crossing functor to the identity functor. The kernel of this…

Representation Theory · Mathematics 2010-02-09 Kevin J. Carlin

This note aims to introduce a left adjoint functor to the functor which assigns a heap to a group. The adjunction is monadic. It is explained how one can decompose a free group functor through the previously introduced adjoint and employ it…

Group Theory · Mathematics 2021-01-19 Bernard Rybołowicz

Let $\mathfrak{g}$ and $\mathfrak{h}$ be two Lie algebras with $\mathfrak{h}$ finite dimensional and consider ${\mathcal A} = {\mathcal A} (\mathfrak{h}, \, \mathfrak{g})$ to be the corresponding universal algebra as introduced in…

Rings and Algebras · Mathematics 2024-06-26 A. L. Agore

We study the end-behavior of integer-valued FI-modules. Our first result describes the high degrees of an FI-module in terms of newly defined tail invariants. Our main result provides an equivalence of categories between FI-tails and…

Representation Theory · Mathematics 2019-09-24 Peter Patzt , John D. Wiltshire-Gordon

Derived functors (or Zuckerman functors) play a very important role in the study of unitary representations of real reductive groups. These functors are usually applied on highest weight modules in the so-called good range and the theory is…

Representation Theory · Mathematics 2013-10-25 Jia-jun Ma

A correspondence functor is a functor from the category of finite sets and correspondences to the category of k-modules, where k is a commu-tative ring. A main tool for this study is the construction of a correspondence functor associated…

Representation Theory · Mathematics 2019-02-15 Serge Bouc , Jacques Thévenaz

This paper describes several cases of adjunction in the homomorphism preorder of relational structures. We say that two functors $\Lambda$ and $\Gamma$ between thin categories of relational structures are adjoint if for all structures…

Combinatorics · Mathematics 2024-04-10 Víctor Dalmau , Andrei Krokhin , Jakub Opršal

Let $L$ be a finite-dimensional Lie algebra over a field of non-zero characteristic and let $S$ be a subalgebra. Suppose that $X$ is a finite set of finite-dimensional $L$-modules. Let $D$ be the category of all finite-dimensional…

Rings and Algebras · Mathematics 2016-09-15 Donald W. Barnes