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The introduction of the categorical notion of closure operators has unified various important notions and has led to interesting examples and applications in diverse areas of mathematics (see for example, Dikranjan and Tholen (\cite{DT})).…

Category Theory · Mathematics 2010-10-22 Joaquin Luna-Torres , Carlos Orlando Ochoa C

Cobordism categories are known to be compact closed. They can therefore be used to define non-degenerate models of multiplicative linear logic by combining the Int construction with double glueing. In this work we detail such construction…

Logic in Computer Science · Computer Science 2023-10-31 Valentin Maestracci , Thomas Seiller

We investigate the polynomial closure operation (C -> Pol(C)) defined on classes of regular languages. We present an interesting and useful connection relating the separation problem for the class C and the membership problem for it…

Formal Languages and Automata Theory · Computer Science 2018-02-20 Thomas Place , Marc Zeitoun

A closure operator on a set $X$ is a function $\operatorname{cl}: \wp(X) \to \wp(X)$ satisfying, for all $A, B \subseteq X$, the following properties: extensivity, $A \subseteq \operatorname{cl}(A)$; monotonicity, which states that if $A…

Combinatorics · Mathematics 2026-03-17 Paulo Magalhães Junior , Renan Maneli Mezabarba , Rodrigo Santos Monteiro

In this paper, necessary and sufficient conditions are established for the factorization of a closed, in general, unbounded operator $T=AB$ into a product of two nonnegative selfadjoint operators $A$ and $B.$ Already the special case, where…

Functional Analysis · Mathematics 2025-07-22 Yosra Barkaoui , Seppo Hassi

The categories with noninvertible morphisms are studied analogously to the semisupermanifolds with noninvertible transition functions. The concepts of regular n-cycles, obstruction and the regularization procedure are introduced and…

Mathematical Physics · Physics 2007-05-23 Steven Duplij , Wladyslaw Marcinek

Coherence theorems for covariant structures carried by a category have traditionally relied on the underlying term rewriting system of the structure being terminating and confluent. While this holds in a variety of cases, it is not a…

Category Theory · Mathematics 2007-05-31 Jonathan A. Cohen

We consider closure properties in the class of positively decreasing distributions. Our results stem from different types of dependence, but each type belongs in the family of asymptotically independent dependence structure. Namely we…

As an example of the categorical apparatus of pseudo algebras over 2-theories, we show that pseudo algebras over the 2-theory of categories can be viewed as pseudo double categories with folding or as appropriate 2-functors into…

Category Theory · Mathematics 2011-11-09 Thomas M. Fiore

In this paper, we study the differential power operation on ideals. We begin with a focus on monomial ideals in characteristic 0 and find a class of ideals whose differential powers are eventually principal. We also study the containment…

Commutative Algebra · Mathematics 2026-03-18 Jennifer Kenkel , Lillian McPherson , Janet Page , Daniel Smolkin , Monroe Stephenson , Fuxiang Yang

In this paper we extensively investigate the class of conditionally positive definite operators, namely operators generating conditionally positive definite sequences. This class itself contains subnormal operators, $2$- and $3$-isometries…

Functional Analysis · Mathematics 2022-01-26 Zenon Jan Jabłoński , Il Bong Jung , Jan Stochel

We consider sets of operations on a set A that are closed under permutation of variables, addition of dummy variables and composition. We describe these closed sets in terms of a Galois connection between operations and systems of pointed…

Rings and Algebras · Mathematics 2016-11-22 Miguel Couceiro , Erkko Lehtonen

We want to replace categories, functors and natural transformations by categories, open functors and open natural transformations. In analogy with open dynamical systems, the adjective open is added here to mean that some external…

Category Theory · Mathematics 2021-02-17 Alexandre Fernandez , Luidnel Maignan , Antoine Spicher

The purpose of this paper is to introduce a consistent notion of universal and reduced crossed products by actions and coactions of groups on operator systems and operator spaces. In particular we shall put emphasis to reveal the full power…

Operator Algebras · Mathematics 2019-10-16 Massoud Amini , Siegfried Echterhoff , Hamed Nikpey

It has long been known that every weak monoidal category A is equivalent via monoidal functors and monoidal natural transformations to a strict monoidal category st(A). We generalise the definition of weak monoidal category to give a…

Category Theory · Mathematics 2007-05-23 Miles Gould

We study the complexity of closure operators, with applications to machine learning and decision theory. In machine learning, closure operators emerge naturally in data classification and clustering. In decision theory, they can model…

Theoretical Economics · Economics 2022-05-25 Hamed Hamze Bajgiran , Federico Echenique

We define and discuss properties of the class of unbounded operators which attain minimum modulus. We establish a relationship between this class and the class of norm attaining bounded operators and compare the properties of both. Also we…

Functional Analysis · Mathematics 2019-04-10 S. H. Kulkarni , G. Ramesh

For topological spaces $X$ and $Y$, a (not necessarily continuous) function $f:X \rightarrow Y$ naturally induces a functor from the category of closed subsets of $X$ (with morphisms given by inclusions) to the category of closed subsets of…

Category Theory · Mathematics 2014-08-13 Edward S. Letzter

It is well known that strict $\omega$-categories, strict $\omega$-functors, strict natural $\omega$-transformations, and so on, form a strict $\omega$-category. A similar property for weak $\omega$-categories is one of the main hypotheses…

K-Theory and Homology · Mathematics 2012-11-13 Kachour Camell

In model selection problems for machine learning, the desire for a well-performing model with meaningful structure is typically expressed through a regularized optimization problem. In many scenarios, however, the meaningful structure is…

Optimization and Control · Mathematics 2022-11-09 Jonathan Bunton , Paulo Tabuada