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We prove that thick category $\mathcal{O}$ associated to a semi-simple complex finite dimensional Lie algebra is extension full in the category of all modules. We also prove the weak Alexandru conjecture both for regular blocks of thick…

Representation Theory · Mathematics 2015-08-05 Kevin Coulembier , Volodymyr Mazorchuk

In this paper, firstly, we introduce a higher-dimensional analogue of hypergraphs, namely $\omega$-hypergraphs. This notion is thoroughly flexible because unlike ordinary $\omega$-graphs, an n-dimensional edge called an n-cell has many…

Category Theory · Mathematics 2007-05-23 Hiroyuki Miyoshi , Toru Tsujishita

In this paper, we propose a weak regularity principle which is similar to both weak K\"onig's lemma and Ramsey's theorem. We begin by studying the computational strength of this principle in the context of reverse mathematics. We then…

Logic · Mathematics 2013-02-12 Stephen Flood

We show in Bishop's constructive mathematics---in particular, using countable choice---that weak K\"{o}nig's lemma implies the uniform continuity theorem.

Logic · Mathematics 2016-11-09 Matthew Hendtlass

We give a unified direct proof of the lifting of PIE limits to the 2-category of algebras and (pseudo) morphisms, which specifies precisely which of the projections of the lifted limit are strict and detect strictness. In the literature,…

Category Theory · Mathematics 2020-03-26 Martin Szyld

To a bicomplex one can associate two natural filtrations, the column and row filtrations, and then two associated spectral sequences. This can be generalized to $N$-multicomplexes. We present a family of model category structures on the…

Algebraic Topology · Mathematics 2025-11-11 Joana Cirici , Muriel Livernet , Sarah Whitehouse

We develop some techniques to the study of exact module categories over some families of pointed finite-dimensional Hopf algebras. As an application we classify exact module categories over the tensor category of representations of the…

Quantum Algebra · Mathematics 2009-06-23 Martin Mombelli

We generalize Kirchberg's weak exactness to inclusions of C*-algebras in von Neumann algebras and study some characterizations and permanence properties which are similar to those of exact groups. We then consider a similar condition to…

Operator Algebras · Mathematics 2014-01-28 Yusuke Isono

This paper presents a necessary and sufficient condition on a category with weak finite limits for its exact completion to be (locally) cartesian closed. A paper by Carboni and Rosolini already claimed such a characterisation using a…

Category Theory · Mathematics 2020-05-21 Jacopo Emmenegger

Both algebraic and computational approaches for dealing with similarity spaces are well known in generalized rough set theory. However, these studies may be said to have been confined to particular perspectives of distinguishability in the…

Logic · Mathematics 2009-05-14 A. Mani

Let $\mathscr{A}$ be an extension closed proper abelian subcategory of a triangulated category $\mathscr{T}$, with no negative 1 and 2 extensions. From this, two functors from $\Sigma\mathscr{A}\ast\mathscr{A}$ to $\mathscr{A}$ can be…

Representation Theory · Mathematics 2023-10-19 Anders S. Kortegaard

This paper gives a uniform-theoretic refinement of classical homotopy theory. Both cubical sets (with connections) and uniform spaces admit classes of weak equivalences, special cases of classical weak equivalences, appropriate for the…

Algebraic Topology · Mathematics 2021-09-20 Sanjeevi Krishnan , Crichton Ogle

Spurred by the new examples found by Kornel Szlach\'anyi of a form of lax monoidal category, the author felt the time ripe to publish a reworking of Eilenberg-Kelly's original paper on closed categories appropriate to the laxer context. The…

Category Theory · Mathematics 2012-09-04 Ross Street

Category theory is the language of homological algebra, allowing us to state broadly applicable theorems and results without needing to specify the details for every instance of analogous objects. However, authors often stray from the realm…

General Mathematics · Mathematics 2025-02-04 Skyler Marks

We prove that rationally connected varieties over the function field of a complex curve satisfy weak approximation for places of good reduction.

Algebraic Geometry · Mathematics 2009-11-10 Brendan Hassett , Yuri Tschinkel

Starting from a description of various generalized function algebras based on sequence spaces, we develop the general framework for considering linear problems with singular coefficients or non linear problems. Therefore, we prove…

Functional Analysis · Mathematics 2007-05-23 Antoine Delcroix , Maximilian F. Hasler , Stevan Pilipović , Vincent Valmorin

The purpose of this short and elementary note is to identify some classes of exact categories introduced in L. Previdi's thesis. Among other things we show: (1) An exact category is partially abelian exact if and only if it is abelian. (2)…

Category Theory · Mathematics 2021-10-05 Theo Buehler

Zalcman's Lemma makes significant applications in normal families, complex dynamics and related problems in complex analysis. In the present paper, we are devoted to generalizing the classical Zalcman's lemma to complex Lie groups by means…

Complex Variables · Mathematics 2025-12-09 Xianjing Dong , Yanda Lv

Given a thick subcategory of a triangulated category, we define a colocalisation and a natural long exact sequence that involves the original category and its localisation and colocalisation at the subcategory. Similarly, we construct a…

Category Theory · Mathematics 2015-10-23 Hvedri Inassaridze , Tamaz Kandelaki , Ralf Meyer

The diagonal lemma asserts that if a map of bisimplicial sets is a levelwise weak equivalence in the Kan-Quillen model structure, then it induces a weak equivalence of the diagonal simplicial sets. In this short note, we observe that the…

Algebraic Topology · Mathematics 2025-12-23 Daniel Carranza , Chris Kapulkin , Liang Ze Wong