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This article is the last of the series of articles where we reprove the foundational ideas of abstract six-functor formalisms developed by Liu-Zheng. We prove the theorem of partial adjoints, which is a simplicial technique of encoding…

Algebraic Geometry · Mathematics 2025-02-03 Chirantan Chowdhury

The usual coherence theorem of MacLane for categories with multiplication assumes that a certain pentagonal diagram commutes in order to conclude that associativity isomorphisms are well defined in a certain practical sense. The practical…

Category Theory · Mathematics 2013-09-04 Matthew G. Brin

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

In this paper we introduce Commutative/Non-Commutative Logic (CNC logic) and two categorical models for CNC logic. This work abstracts Benton's Linear/Non-Linear Logic by removing the existence of the exchange structural rule. One should…

Logic in Computer Science · Computer Science 2019-04-16 Jiaming Jiang , Harley Eades , Valeria de Paiva

We study locally constant coefficients. We first study the theory of homotopy Kan extensions with locally constant coefficients in model categories, and explain how it characterizes the homotopy theory of small categories. We explain how to…

Algebraic Topology · Mathematics 2009-12-12 Denis-Charles Cisinski

The structure of the category of matroids and strong maps is investigated: it has coproducts and equalizers, but not products or coequalizers; there are functors from the categories of graphs and vector spaces, the latter being faithful;…

Category Theory · Mathematics 2020-12-03 Chris Heunen , Vaia Patta

In this paper, we describe an algorithm for computing the left, right, or 2-sided congruences of a finitely presented semigroup or monoid with finitely many classes, and an alternative algorithm when the finitely presented semigroup or…

Rings and Algebras · Mathematics 2025-06-26 Marina Anagnostopoulou-Merkouri , Reinis Cirpons , James D. Mitchell , Maria Tsalakou

We investigate several categories related to transition structures, using a mixture of algebraic and topological methods. We show how two such categories are connected by a contravariant adjunction. This is the most detailed of a family of…

Category Theory · Mathematics 2026-04-16 Matthew Collinson

A new proof for adjoint systems of linear equations is presented. The argument is built on the principles of Algorithmic Differentiation. Application to scalar multiplication sets the base line. Generalization yields adjoint inner vector,…

Numerical Analysis · Mathematics 2025-10-20 Uwe Naumann

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

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

For each pair of lax-idempotent pseudomonads $R$ and $I$, for which $I$ is locally fully faithful and $R$ distributes over $I$, we establish an adjoint functor theorem, relating $R$-cocontinuity to adjointness relative to $I$. This provides…

Category Theory · Mathematics 2025-10-16 Nathanael Arkor , Ivan Di Liberti , Fosco Loregian

We construct an abelian category C and exact functors in C which on the Grothendieck group descend to the action of a simply-laced quantum group in its adjoint representation. The braid group action in the adjoint representation lifts to an…

Quantum Algebra · Mathematics 2007-05-23 Ruth Stella Huerfano , Mikhail Khovanov

We prove a class of equivalences of additive functor categories that are relevant to enumerative combinatorics, representation theory, and homotopy theory. Let $\mathscr{X}$ denote an additive category with finite direct sums and split…

Category Theory · Mathematics 2019-04-01 Stephen Lack , Ross Street

In this mainly expository note, we state a criterion for when a left Kan extension of a lax monoidal functor along a strong monoidal functor can itself be equipped with a lax monoidal structure, in a way that results in a left Kan extension…

Category Theory · Mathematics 2018-09-28 Tobias Fritz , Paolo Perrone

To provide a categorical semantics for co-intuitionistic logic one has to face the fact, noted by Tristan Crolard, that the definition of co-exponents as adjuncts of coproducts does not work in the category Set, where coproducts are…

Logic in Computer Science · Computer Science 2015-07-01 Gianluigi Bellin

We distinguish between faint, weak, strong and strict localizations of categories at morphism families and show that this framework captures the different types of derived functors that are considered in the literature. More precisely, we…

Algebraic Topology · Mathematics 2021-09-28 Alisa Govzmann , Damjan Pištalo , Norbert Poncin

We prove that the bounded derived category of coherent sheaves with proper support is equivalent to the category of locally-finite, cohomological functors on the perfect derived category of a quasi-projective scheme over a field. We…

Algebraic Geometry · Mathematics 2011-05-18 Matthew Robert Ballard

As left adjoint to the dual algebra functor, Sweedler's finite dual construction is an important tool in the theory of Hopf algebras over a field. We show in this note that the left adjoint to the dual algebra functor, which exists over…

Category Theory · Mathematics 2018-03-02 Hans-E. Porst , Ross Street

We give a general method to build categories of combinatorial manifolds, i.e. categories of combinatorial objects satisfying some local property at every "point", as coreflective subcategories of categories of relational presheaves. To do…

Category Theory · Mathematics 2026-05-21 Yorgo Chamoun