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We consider the question of simultaneous extension of (pseudo)metrics defined on nonempty closed subsets of a compact metrizable space. The main result is a counterpart of the result due to K\"unzi and Shapiro for the case of extension…

General Topology · Mathematics 2007-05-23 E. D. Tymchatyn , M. Zarichnyi

In this paper we introduce and study a new sequence of positive linear operators acting on function spaces defined on a convex compact subset. Their construction depends on a given Markov operator, a positive real number and a sequence of…

Functional Analysis · Mathematics 2017-10-18 Francesco Altomare , Mirella Cappelletti Montano , Vita Leonessa , Ioan Rasa

The concept of complementability is extended from bounded operators to densely defined operators on Hilbert spaces. By introducing appropriate projections and decomposition techniques, a framework is developed for analyzing…

Functional Analysis · Mathematics 2025-11-27 Sachin Manjunath Naik , P. Sam Johnson

There are presented certain results on extending continuous linear operators defined on spaces of E-valued continuous functions (defined on a compact Hausdorff space X) to linear operators defined on spaces of E-valued measurable functions…

Functional Analysis · Mathematics 2017-05-26 Piotr Niemiec

We characterize the compactness of composition operators; in term of generalized Nevanlinna counting functions, on a large class of Hilbert spaces of analytic functions, which can be viewed between the Bergman and the Dirichlet spaces

Functional Analysis · Mathematics 2010-05-02 Karim Kellay , Pascal Lefèvre

We study spaces of essentially bounded functions on compact subsets of the real line, equipped with the Alexiewicz norm given by the supremum norm of the primitive. Using the associated measure projection, we classify their surjective…

Functional Analysis · Mathematics 2026-03-30 Nuno J. Alves

In this paper we study some geometric properties like parallelism, orthogonality and semi-rotundity in the space of bounded linear operators. We completely characterize parallelism of two compact linear operators between normed linear…

Functional Analysis · Mathematics 2024-08-13 Arpita Mal , Debmalya Sain , Kallol Paul

It is proved recently by Benamara-Nikolski that a contraction having finite defects and spectrum not filling in the closed unit disc, is similar to a normal operator if and only if it has the so-called linear resolvent growth property. We…

Spectral Theory · Mathematics 2007-05-23 Stanislav Kupin

Continuing the study initiated in our earlier article [7], this paper aims to characterize various continuity properties of nonlinear composition operators acting on some sequence spaces, giving special attention to the space of sequences…

Functional Analysis · Mathematics 2025-05-13 Daria Bugajewska , Piotr Kasprzak

We construct a topology on the standard Hilbert module $l^2(\mathcal A)$ over a unital $W^*$-algebra $\mathcal A$ such that any "compact" operator, (i.e.\ any operator in the norm closure of the linear span of the operators of the form…

Operator Algebras · Mathematics 2018-05-23 Dragoljub J Kečkić , Zlatko Lazović

We study universal approximation of continuous functionals on compact subsets of products of Hilbert spaces. We prove that any such functional can be uniformly approximated by models that first take finitely many continuous linear…

Machine Learning · Computer Science 2026-02-04 Andrey Krylov , Maksim Penkin

We give a characterization of the compact operators on a model space in terms of asymptotic Toeplitz operators.

Functional Analysis · Mathematics 2016-03-07 Isabelle Chalendar , William T. Ross

A map between operator spaces is called completely coarse if the sequence of its amplifications is equi-coarse. We prove that all completely coarse maps must be $\mathbb R$-linear. On the opposite direction of this result, we introduce a…

Operator Algebras · Mathematics 2020-06-02 Bruno M. Braga , Javier Alejandro Chávez-Domínguez

In the work it is shown that the space of idempotent probability measures with compact supports is kappa-metrizable if the given Tychonoff space is kappa-metrizable. It is constructed a series of max-plus-convex subfunctors of the functor…

General Topology · Mathematics 2019-05-23 Azad Yangibayevich Ishmetov

We provide an example of a zero-dimensional compact metric space $X$ and its closed subspace $A$ such that there is no continuous linear extension operator for the Lipschitz pseudometrics on $A$ to the Lipschitz pseudometrics on $X$. The…

General Topology · Mathematics 2007-05-23 Michael Zarichnyi

We introduce the notion of functionally compact sets into the theory of nonlinear generalized functions in the sense of Colombeau. The motivation behind our construction is to transfer, as far as possible, properties enjoyed by standard…

Functional Analysis · Mathematics 2016-03-01 Paolo Giordano , Michael Kunzinger

For a very general class of weighted Fock spaces on $\mathbb{C}^n$, we give necessary and sufficient conditions for a Toeplitz operator with a (not necessarily positive) measure symbol to be compact. Furthermore, we show that all compact…

Functional Analysis · Mathematics 2013-06-04 Joshua Isralowitz

We study the typical behavior of bounded linear operators on infinite dimensional complex separable Hilbert spaces in the norm, strong-star, strong, weak polynomial and weak topologies. In particular, we investigate typical spectral…

Functional Analysis · Mathematics 2014-05-01 Tanja Eisner , Tamas Matrai

General, especially spectral, features of compact normal operators in quaternionic Hilbert spaces are studied and some results are established which generalize well-known properties of compact normal operators in complex Hilbert spaces.…

Functional Analysis · Mathematics 2014-02-14 Riccardo Ghiloni , Valter Moretti , Alessandro Perotti

We continue the study of multidimensional operator multipliers initiated in [arXiv:math/0701645]. We introduce the notion of the symbol of an operator multiplier. We characterise completely compact operator multipliers in terms of their…

Operator Algebras · Mathematics 2015-02-06 K. Juschenko , R. H. Levene , I. G. Todorov , L. Turowska