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Pronk's theorem on bicategories of fractions is applied, in almost all cases in the literature, to 2-categories of geometrically presentable stacks on a 1-site. We give an proof that subsumes all previous such results and which is purely…

Category Theory · Mathematics 2018-02-02 David Michael Roberts

The distributive property can be studied through bilinear maps and various morphisms between these maps. The adjoint-morphisms between bilinear maps establish a complete abelian category with projectives and admits a duality. Thus the…

Category Theory · Mathematics 2012-05-04 James B. Wilson

The notion of a duality between two derived functors as well as an extension theorem for derived functors to larger categories in which they need not be defined is introduced. These ideas are then applied to extend and study the coext…

Rings and Algebras · Mathematics 2014-02-19 Anastasis Kratsios

We make precise the structure of the first two reduction morphisms associated with codimension two nonsingular subvarieties of quadrics $\Q{n}$, $n\geq 5$. We give a coarse classification of the same class of subvarieties when they are…

alg-geom · Mathematics 2008-02-03 Mark Andrea A. de Cataldo

We present the notion of "cyclic double multicategory", as a structure in which to organise multivariable adjunctions and mates. The classic example of a 2-variable adjunction is the hom/tensor/cotensor trio of functors; we generalise this…

Category Theory · Mathematics 2012-08-24 Eugenia Cheng , Nick Gurski , Emily Riehl

We study mixed identities for oligomorphic automorphism groups of countable relational structures. Our main result gives sufficient conditions for such a group to not admit a mixed identity without particular constants. We study numerous…

Group Theory · Mathematics 2025-08-20 Manuel Bodirsky , Jakob Schneider , Andreas Thom

Given a pair of adjoint functors between two arbitrary categories it induces mutually inverse equivalences between the full subcategories of the initial ones, consisting of objects for which the arrows of adjunction are isomorphisms. We…

Category Theory · Mathematics 2009-10-22 George Ciprian Modoi

We develop a 2-dimensional version of accessibility and presentability compatible with the formalism of flat pseudofunctors. First we give prerequisites on the different notions of 2-dimensional colimits, filteredness and cofinality; in…

Category Theory · Mathematics 2025-08-05 Ivan Di Liberti , Axel Osmond

This second part comes to the construction of the spectrum associated to a situation of multi-adjunction. Exploiting a geometric understanding of its multi-versal property, the spectrum of an object is obtained as the spaces of local units…

Category Theory · Mathematics 2021-04-07 Axel Osmond

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

We develop the theory of relative monads and relative adjunctions in a virtual equipment, extending the theory of monads and adjunctions in a 2-category. The theory of relative comonads and relative coadjunctions follows by duality. While…

Category Theory · Mathematics 2025-10-21 Nathanael Arkor , Dylan McDermott

There are many contexts in algebraic geometry, algebraic topology, and homological algebra where one encounters a functor that has both a left and right adjoint, with the right adjoint being isomorphic to a shift of the left adjoint…

Algebraic Topology · Mathematics 2007-05-23 H. Fausk , P. Hu , J. P. May

We extend the 2-representation theory of finitary 2-categories to certain 2-categories with infinitely many objects, denoted locally finitary 2-categories, and extend the classical classification results of simple transitive…

Category Theory · Mathematics 2022-01-19 James Macpherson

We introduce pseudoalgebras for relative pseudomonads and develop their theory. For each relative pseudomonad $T$, we construct a free--forgetful relative pseudoadjunction that exhibits the bicategory of $T$-pseudoalgebras as terminal among…

Category Theory · Mathematics 2025-01-23 Nathanael Arkor , Philip Saville , Andrew Slattery

2-Theories are a canonical way of describing categories with extra structure. 2-theory-morphisms are used when discussing how one structure can be replaced with another structure. This is central to categorical coherence theory. We place a…

Category Theory · Mathematics 2007-05-23 Noson S. Yanofsky

In earlier papers, we showed a decomposition of the arcs of 2-diregular digraphs (2-dds) and used it to prove some conditions for these graphs to be non-Hamiltonian; we then extended this decomposition to a larger class of digraphs and used…

Combinatorics · Mathematics 2026-01-27 Munagala V. Ramanath

We study limits in 2-categories whose objects are categories with extra structure and whose morphisms are functors preserving the structure only up to a coherent comparison map, which may or may not be required to be invertible. This is…

Category Theory · Mathematics 2012-02-20 Stephen Lack , Michael Shulman

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

We define strict and weak duality involutions on 2-categories, and prove a coherence theorem that every bicategory with a weak duality involution is biequivalent to a 2-category with a strict duality involution. For this purpose we…

Category Theory · Mathematics 2018-01-26 Michael Shulman

We give a new criterion guaranteeing existence of model structures left-induced along a functor admitting both adjoints. This works under the hypothesis that the functor induces idempotent adjunctions at the homotopy category level. As an…

Category Theory · Mathematics 2022-10-25 Philip Hackney , Martina Rovelli