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Adjunctions of two variables generalize the relationship between tensor product and the internal hom functor in a closed monoidal category. For a pair of ordinary adjunctions $(F\dashv U, F'\dashv U')$ conjugation relates natural…

Category Theory · Mathematics 2025-01-06 Simon Willerton

Relational presheaves generalize traditional presheaves by going to the category of sets and relations (as opposed to sets and functions) and by allowing functors which are lax. This added generality is useful because it intuitively allows…

Category Theory · Mathematics 2025-12-10 Yorgo Chamoun , Samuel Mimram

We construct an explicit combinatorial model of the functor which adds right adjoints to the morphisms of an $\infty$-category, and we speculate on possible extensions to higher dimensions.

Category Theory · Mathematics 2025-10-08 Lorenzo Riva , Martina Rovelli

The aim of this paper is to present a very simple original, purely formal, proof of Quillen's adjunction theorem for derived functors, and of some more recent variations and generalizations of this theorem. This is obtained by proving an…

Algebraic Topology · Mathematics 2007-05-23 Georges Maltsiniotis

We establish a Galois connection between sub-monads of an augmented monad and sub-functors of the forgetful functor from its Eilenberg-Moore category. This connection is given in terms of invariants and stabilizers defined through universal…

Category Theory · Mathematics 2021-06-09 Johan Felipe García Vargas

We construct an adjunction between $m$-categories internal to $(\infty,n)$-categories, called $(n,m)$-double $\infty$-categories, and filtrations $A_0\to \dots\to A_m$ where for all $i<m$, $A_i$ is a $(n+i)$-category. We show that this…

Category Theory · Mathematics 2025-03-26 Félix Loubaton

These are the notes for a minicourse held in Odessa (2016) and Belo Horizonte (2017). My aim was to provide a short introduction to basic notions of category theory and representation theory of finite-dimensional algebras. We learnt the…

Representation Theory · Mathematics 2017-04-26 Kostiantyn Iusenko

We make explicit certain results around the Galois correspondence in the context of definable automorphism groups, and point out the relation to some recent papers dealing with the Galois theory of algebraic differential equations when the…

Logic · Mathematics 2016-07-20 Omar Leon Sanchez , Anand Pillay

A functor of sets $\mathbb X$ over the category of $K$-commutative algebras is said to be an affine functor if its functor of functions, $\mathbb A_{\mathbb X}$, is reflexive and $\mathbb X=\Spec \mathbb A_{\mathbb X}$. We prove that affine…

Algebraic Geometry · Mathematics 2012-05-08 J. Navarro , C. Sancho , P. Sancho

We discuss generalised duality theory for monoidal categories and its applications to the categories of exact endofunctors, graded vector spaces, and topological vector spaces.

Category Theory · Mathematics 2023-01-25 Stefan Zetzsche

{\em Galois comodules} over a coring can be characterised by properties of the relative injective comodules. They motivated the definition of {\em Galois functors} over some comonad (or monad) on any category and in the first section of the…

Category Theory · Mathematics 2009-10-01 Bachuki Mesablishvili , Robert Wisbauer

From every pair of adjoint functors it is possible to produce a (possibly trivial) equivalence of categories by restricting to the subcategories where the unit and counit are isomorphisms. If we do this for the adjunction between effect…

Logic in Computer Science · Computer Science 2019-01-30 Robert Furber

In the context of infinity categories, we rethink the notion of derived functor in terms of correspondences. This is especially convenient for the description of a passage from an adjoint pair (F,G) of functors to a derived adjoint pair…

Category Theory · Mathematics 2020-03-25 V. Hinich

We study the relationship between cartesian bicategories and a specialisation of Lawvere's hyperdoctrines, namely elementary existential doctrines. Both provide different ways of abstracting the structural properties of logical systems: the…

Logic in Computer Science · Computer Science 2021-11-09 Filippo Bonchi , Alessio Santamaria , Jens Seeber , Paweł Sobociński

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

To a Lie groupoid over a compact base, the associated group of bisection is an (infinite-dimensional) Lie group. Moreover, under certain circumstances one can reconstruct the Lie groupoid from its Lie group of bisections. In the present…

Category Theory · Mathematics 2019-02-20 Alexander Schmeding , Christoph Wockel

Approximation of entire functions by their pad\'e approximants has been examined in the past. It is true that generically such an approximation holds. However, examining this problem from another viewpoint, we obtain stronger generic…

Complex Variables · Mathematics 2011-05-17 G. Fournodavlos

We develop a bicategorical setup in which one can speak about adjoint 1-morphisms even in the absence of genuine identity 1-morphisms. We also investigate which part of 2-representation theory of 2-categories extends to this new setup.

Category Theory · Mathematics 2020-03-11 Hankyung Ko , Volodymyr Mazorchuk , Xiaoting Zhang

Perhaps the most important contribution of gauge theory to general mathematics is to point out the importance of association functors. Emphasizing category theory we characterize association functors by two of their natural properties and…

Differential Geometry · Mathematics 2022-07-29 Gustavo Amilcar Saldaña Moncada , Gregor Weingart

A Datalog program can be viewed as a syntactic specification of a functor from database instances over some schema to database instances over another schema. The same holds more generally for $\exists$Datalog. We establish large classes of…

Logic in Computer Science · Computer Science 2023-02-14 Balder ten Cate , Víctor Dalmau , Jakub Opršal