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This is the second paper in a series. In part I we developed deformation theory of objects in homotopy and derived categories of DG categories. Here we extend these (derived) deformation functors to an appropriate bicategory of artinian DG…

Algebraic Geometry · Mathematics 2018-08-13 Alexander I. Efimov , Valery A. Lunts , Dmitri O. Orlov

We endow the set of complements of a fixed subspace of a projective space with the structure of an affine space, and show that certain lines of such an affine space are affine reguli or cones over affine reguli. Moreover, we apply our…

Algebraic Geometry · Mathematics 2024-02-13 Andrea Blunck , Hans Havlicek

We introduce the notion of star-symmetry for relations in a multi-pointed category and use it to obtain a characterization of the projective covers of 2-star-permutable categories. This generalizes the results of Rosick\'y-Vitale for…

Category Theory · Mathematics 2019-10-31 Vasileios Aravantinos-Sotiropoulos

We develop the theory of categories of measurable fields of Hilbert spaces and bounded fields of bounded operators. We examine classes of functors and natural transformations with good measure theoretic properties, providing in the end a…

Category Theory · Mathematics 2007-05-23 D. N. Yetter

We describe a duality for quantale-enriched categories that extends the Lawson duality for continuous dcpos: for any saturated class J of modules that commute with certain weighted limits, and under an appropriate choice of morphisms, the…

Category Theory · Mathematics 2010-12-16 Dirk Hofmann , Pawel Waszkiewicz

In this technical note, we proffer a very explicit construction of the "dual cocartesian fibration" $p^{\vee}$ of a cartesian fibration $p$, and we show they are classified by the same functor to $\mathbf{Cat}_{\infty}$.

Category Theory · Mathematics 2014-09-09 Clark Barwick , Saul Glasman , Denis Nardin

Prolongations of a group extension can be studied in a more general situation that we call group extensions of the co-type of a crossed module. Cohomology classification of such extensions is obtained by applying the obstruction theory of…

Category Theory · Mathematics 2015-03-17 Nguyen Tien Quang

Given a small category C, we show that there is a universal way of expanding C into a model category, essentially by formally adjoining homotopy colimits. The technique of localization becomes a method for imposing `relations' into these…

Algebraic Topology · Mathematics 2007-05-23 Daniel Dugger

Category theory unifies mathematical concepts, aiding comparisons across structures by incorporating objects and morphisms, which capture their interactions. It has influenced areas of computer science such as automata theory, functional…

Category Theory · Mathematics 2024-02-09 Nima Rasekh , Niels van der Weide , Benedikt Ahrens , Paige Randall North

The main aim of this paper is to generalize the classical concept of positive operator, and to develop a general extension theory, which overcomes not only the lack of a Hilbert space structure, but also the lack of a normable topology. The…

Functional Analysis · Mathematics 2018-10-08 Zsigmond Tarcsay , Tamás Titkos

We develop a theory of double clubs which extends Kelly's theory of clubs to the pseudo double categories of Pare and Grandis. We then show that the club for symmetric strict monoidal categories on Cat extends to a `double club' on the…

Category Theory · Mathematics 2007-06-26 Richard Garner

The problem of bi-equivariant extension of continuous maps of binary $G$-spaces is considered. The concept of a structural map of distributive binary $G$-spaces is introduced, and a theorem on the bi-equivariant extension of structural maps…

General Topology · Mathematics 2025-09-11 Pavel S. Gevorgyan

A certain amount of category theory is developed in an arbitrary finitely complete category with a factorization system on it, playing the role of the comprehensive factorization system on Cat. Those aspects related to the concepts of…

Category Theory · Mathematics 2007-09-07 Claudio Pisani

This survey article on bivariant Kasparov theory and E-theory is mainly intended for readers with a background in homotopical algebra and category theory. We approach both bivariant K-theories via their universal properties and equip them…

K-Theory and Homology · Mathematics 2015-10-23 Ralf Meyer

The goal of this work is to describe a categorical formalism for (Extended) Topological Quantum Field Theories (TQFTs) and present them as functors from a suitable category of cobordisms with corners to a linear category, generalizing 2d…

Quantum Algebra · Mathematics 2011-08-29 Mark Feshbach , Alexander A. Voronov

In this thesis weighted colimits in 2-categories equipped with promorphisms are studied. Such colimits include most universal constructions with counits, like ordinary colimits in categories, weighted colimits in enriched categories, and…

Category Theory · Mathematics 2013-04-16 Seerp Roald Koudenburg

This paper introduces the notion of weakly globular double categories, a particular class of strict double categories, as a way to model weak 2-categories; it explores its use in defining a double category of fractions, and shows that the…

Category Theory · Mathematics 2013-03-28 Simona Paoli , Dorette Pronk

In this paper we obtain the genus field of a general Kummer extension of a global rational function field. We study first the case of a general Kummer extension of degree a power of a prime. Then we prove that the genus field of a composite…

Number Theory · Mathematics 2021-05-17 Martha Rzedowski-Calderón , Gabriel Villa-Salvador

The work is devoted to the extension groups in the category of functors from a small category to an additive category with an Abelian structure in the sense of Heller. It is constructed a spectral sequence which converges to the extension…

Category Theory · Mathematics 2009-09-28 A. A. Husainov , A. Pancar , M. Yapici

We propose a definition of double categories whose composition of 1-cells is weak in both directions. Namely, a doubly weak double category is a double computad -- a structure with 2-cells of all possible double-categorical shapes --…

Category Theory · Mathematics 2026-05-25 Aaron David Fairbanks , Michael Shulman