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Voevodsky's derived category of motives is the main arena today for the study of algebraic cycles and motivic cohomology. In this paper we study whether the inclusions of three important subcategories of motives have a left or right…

Algebraic Geometry · Mathematics 2016-03-30 Burt Totaro

We initiate the systematic study of modular representations of symmetric groups that arise via the braiding in (symmetric) tensor categories over fields of positive characteristic. We determine what representations appear for certain…

Representation Theory · Mathematics 2026-03-09 Kevin Coulembier

In this paper we construct two groupoids from morphisms of groupoids, with one from a categorical viewpoint and the other from a geometric viewpoint. We show that for each pair of groupoids, the two kinds of groupoids of morphisms are…

Category Theory · Mathematics 2019-08-16 Bohui Chen , Cheng-Yong Du , Rui Wang

Several models for the Burnside bicategory of groupoids are described and shown to be equivalent. As observed by the late Gaunce Lewis, the corresponding Burnside category is additive.

Algebraic Topology · Mathematics 2016-07-06 Haynes Miller

A natural question in the theory of Tannakian categories is: What if you don't remember $\Forget$? Working over an arbitrary commutative ring $R$, we prove that an answer to this question is given by the functor represented by the \'etale…

Category Theory · Mathematics 2019-11-05 Alexandru Chirvasitu , Theo Johnson-Freyd

We axiomatically define (pre-)Hilbert categories. The axioms resemble those for monoidal Abelian categories with the addition of an involutive functor. We then prove embedding theorems: any locally small pre-Hilbert category whose monoidal…

Category Theory · Mathematics 2010-08-05 Chris Heunen

It is well known that the category of covering projections (that is, locally constant objects) of a locally connected topos is equivalent to the classifying topos of a strict progroupoid (or, equivalently, a localic prodiscrete groupoid),…

Category Theory · Mathematics 2007-06-13 Eduardo J. Dubuc

We prove that the notion of Drinfeld center defines a functor from the category of indecomposable multi-tensor categories with morphisms given by bimodules to that of braided tensor categories with morphisms given by monoidal bimodules.…

Category Theory · Mathematics 2018-10-19 Liang Kong , Hao Zheng

This paper provides several characterizations of final functors between internal groupoids in Barr-exact categories. In particular, it is proved that an internal functor between groupoids is final if and only if it is full and essentially…

Category Theory · Mathematics 2017-11-30 Alan S. Cigoli

We prove that the Jacquet restriction functor for a parabolic subgroup of a reductive group over a non-Archimedean local field is right adjoint to the parabolic induction functor for the opposite parabolic subgroup, in the generality of…

Representation Theory · Mathematics 2010-05-28 Ralf Meyer , Maarten Solleveld

We obtain analogues of classical results on automorphism groups of holomorphic fiber bundles, in the setting of group schemes. Also, we establish a lifting property of the connected automorphism group, for torsors under abelian varieties.…

Algebraic Geometry · Mathematics 2011-06-30 Michel Brion

This is the second introductory paper concerning structures called rootoids and protorootoids, the definition of which is abstracted from formal properties of Coxeter groups with their root systems and weak orders. The ubiquity of…

Group Theory · Mathematics 2011-10-18 Matthew Dyer

Multisorted modules, equivalently representations of quivers, equivalently additive functors on preadditive categories, encompass a wide variety of additive structures. In addition, every module has a natural and useful multisorted…

Representation Theory · Mathematics 2018-08-01 Mike Prest

Every principal G-bundle is classified up to equivalence by a homotopy class of maps into the classifying space of G. On the other hand, for every nice topological space Milnor constructed a strict model of loop space, that is a group.…

Algebraic Topology · Mathematics 2016-02-24 Martina Rovelli

Protoadditive functors are designed to replace additive functors in a non-abelian setting. Their properties are studied, in particular in relationship with torsion theories, Galois theory, homology and factorisation systems. It is shown how…

Category Theory · Mathematics 2015-04-20 Tomas Everaert , Marino Gran

We provide three functorial extensions of the equivalence between localic etale groupoids and their quantales. The main result is a biequivalence between the bicategory of localic etale groupoids, with bi-actions as 1-cells, and a…

Category Theory · Mathematics 2015-10-21 Pedro Resende

In the context of operator-space modules over C*-algebras, we give a complete characterisation of those C*-correspondences whose associated Haagerup tensor product functors admit left adjoints. The characterisation, which builds on previous…

Operator Algebras · Mathematics 2017-02-08 Tyrone Crisp

We prove the theorem stated in the title. More precisely, we show the stronger statement that every symmetric monoidal left adjoint functor between presentably symmetric monoidal infinity-categories is represented by a strong symmetric…

Algebraic Topology · Mathematics 2017-10-03 Thomas Nikolaus , Steffen Sagave

Category theory has foundational importance because it provides conceptual lenses to characterize what is important in mathematics. Originally the main lenses were universal mapping properties and natural transformations. In recent decades,…

Category Theory · Mathematics 2007-05-23 David Ellerman

Every monoidal functor G: C --> M has a canonical factorization through the category of bimodules over some monoid R in M such that the factor U: C -->_R M_R is strongly unital. Using this result and the characterization of the forgetful…

Quantum Algebra · Mathematics 2009-09-29 K. Szlachanyi