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Using the recent theory of Krein--von Neumann extensions for positive functionals we present several simple criteria to decide whether a given positive functional on the full operator algebra is normal. We also characterize those…

Functional Analysis · Mathematics 2017-10-19 Zoltán Sebestyén , Zsigmond Tarcsay , Tamás Titkos

Let $G$ be a reflection group acting on a vector space $V$ and let $\gamma$ be an automorphism of $V$ normalising $G$. We study how $\gamma$ acts on invariants and covariants (for various representations) of $G$, and properties of its…

Group Theory · Mathematics 2008-07-07 Cédric Bonnafé , Gus Lehrer , Jean Michel

We develop the theory of exact completions of regular $\infty$-categories, and show that the $\infty$-categorical exact completion (resp. hypercompletion) of an abelian category recovers the connective half of its bounded (resp. unbounded)…

Category Theory · Mathematics 2023-10-20 Germán Stefanich

Necessary and sufficient conditions for the exactness (in the algebraic sense) of certain sequences of continuous group homomorphisms are established.

Functional Analysis · Mathematics 2025-06-23 Dinamérico P. Pombo

We consider distributions on a closed compact manifold $M$ as maps on smoothing operators. Thus spaces of certain maps between $\Psi^{-\infty}(M)\to \mathcal{C}^{\infty}(M)$ are considered as generalized functions. For any collection of…

Analysis of PDEs · Mathematics 2009-06-09 Shantanu Dave

We prove a general theorem which includes most notions of "exact completion". The theorem is that "k-ary exact categories" are a reflective sub-2-category of "k-ary sites", for any regular cardinal k. A k-ary exact category is an exact…

Category Theory · Mathematics 2012-09-06 Michael Shulman

We study the consistency and consistency strength of various configurations concerning the cardinal characteristics $\mathfrak{s}_\theta,\mathfrak{p}_\theta,\mathfrak{g}_\theta,\mathfrak{r}_\theta,\mathfrak{t}_\theta$ at uncountable regular…

Logic · Mathematics 2021-02-02 Omer Ben-Neria , Shimon Garti

In the category of monoids we characterize monomorphisms that are normal, in an appropriate sense, to internal reflexive relations, preorders or equivalence relations. The zero-classes of such internal relations are first described in terms…

Category Theory · Mathematics 2022-10-10 Nelson Martins-Ferreira , Manuela Sobral

This paper concerns homological notions of regularity for noncommutative algebras. Properties of an algebra $A$ are reflected in the regularities of certain (complexes of) $A$-modules. We study the classical Tor-regularity and…

Rings and Algebras · Mathematics 2025-08-07 Ellen Kirkman , Robert Won , James J. Zhang

We give a number of constructions where inverse limits seriously degrade properties of regular rings, such as unit-regularity, diagonalisation of matrices, and finite stable rank. This raises the possibility of using inverse limits to…

Rings and Algebras · Mathematics 2024-11-21 Pere Ara , Ken Goodearl , Kevin C. O'Meara , Enrique Pardo , Francesc Perera

This paper exhibits some new examples of the behavior of the Castelnuovo-Mumford regularity of homogeneous ideals in polynomial rings. More precisely, we present new examples of homogenous ideals with large regularity compared to the…

Commutative Algebra · Mathematics 2015-08-18 Keivan Borna , Abolfazl Mohajer

We introduce notions of finiteness obstruction, Euler characteristic, L^2-Euler characteristic, and M\"obius inversion for wide classes of categories. The finiteness obstruction of a category Gamma of type (FP) is a class in the projective…

Algebraic Topology · Mathematics 2010-09-22 Thomas M. Fiore , Wolfgang Lück , Roman Sauer

In universal algebra, it is well known that varieties admitting a majority term admit several Mal'tsev-type characterizations. The main aim of this paper is to establish categorical counterparts of some of these characterizations for…

Category Theory · Mathematics 2019-02-20 Michael Hoefnagel

Reflexive polytopes which have the integer decomposition property are of interest. Recently, some large classes of reflexive polytopes with integer decomposition property coming from the order polytopes and the chain polytopes of finite…

Combinatorics · Mathematics 2020-09-08 Takayuki Hibi , Akiyoshi Tsuchiya

Relative realizability toposes satisfy a universal property that involves regular functors to other categories. We use this universal property to define what relative realizability categories are, when based on other categories than of the…

Logic · Mathematics 2013-08-05 Wouter Pieter Stekelenburg

The (co)completeness problem for the (projectively) stable module category of an associative ring is studied. (Normal) monomorphisms and (normal) epimorphisms in such a category are characterized. As an application, we give a criterion for…

Rings and Algebras · Mathematics 2015-01-06 Alex Martsinkovsky , Dali Zangurashvili

Recent work of Lazarovich provides necessary and sufficient conditions on a graph L for there to exist a unique simply-connected (k,L)-complex. The two conditions are symmetry properties of the graph, namely star-transitivity and…

Combinatorics · Mathematics 2013-01-10 Michael Giudici , Cai Heng Li , Akos Seress , Anne Thomas

In this paper our aim is to find the radii of starlikeness and convexity of the generalized Mittag-Leffler function for three different kinds of normalization by using their Hadamard factorization in such a way that the resulting functions…

Complex Variables · Mathematics 2021-01-19 Árpád Baricz , Anuja Prajapati

Let A be a finitely generated associative algebra over an algebraically closed field. We characterize the finite dimensional modules over A whose orbit closures are regular varieties.

Algebraic Geometry · Mathematics 2007-05-23 Nguyen Quang Loc , Grzegorz Zwara

Convergence of projection-based methods for nonconvex set feasibility problems has been established for sets with ever weaker regularity assumptions. What has not kept pace with these developments is analogous results for convergence of…

Optimization and Control · Mathematics 2020-03-26 Aris Daniilidis , D. Russell Luke , Matthew K. Tam