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We investigate strongly separately continuous functions on a product of topological spaces and prove that if $X$ is a countable product of real lines, then there exists a strongly separately continuous function $f:X\to\mathbb R$ which is…

General Topology · Mathematics 2015-08-07 Olena Karlova

We prove that many completeness properties coincide in metric spaces, precompact groups and dense subgroups of products of separable metric groups. We apply these results to function spaces C_p(X,G) of G-valued continuous functions on a…

General Topology · Mathematics 2017-05-26 Alejandro Dorantes-Aldama , Dmitri Shakhmatov

It is shown that a set in product of $n$ metrizable spaces is the discontinuity points set of some separately continuous function if and only if this set can be represented as the union of a sequence of $F_{\sigma}$-sets which are locally…

General Topology · Mathematics 2015-12-29 V. K. Maslyuchenko , V. V. Mykhaylyuk

A subset $A$ of a topological space $X$ is called relatively functionally countable (RFC) in $X$, if for each continuous function $f : X \to \mathbb{R}$ the set $f[A]$ is countable. We prove that all RFC subsets of a product…

General Topology · Mathematics 2024-11-11 Anton Lipin

Every symmetric generating functional of a convolution semigroup of states on a locally compact quantum group is shown to admit a dense unital $*$-subalgebra with core-like properties in its domain. On the other hand we prove that every…

Operator Algebras · Mathematics 2021-07-15 Adam Skalski , Ami Viselter

Transfer operators and Ruelle zeta functions for super-continuous functions on one-sided topological Markov shifts are considered. For every super-continuous function, we construct a Banach space on which the associated transfer operator is…

Dynamical Systems · Mathematics 2020-11-03 Katsukuni Nakagawa

The numerical index of a Banach space is a geometric constant relating the numerical radius of bounded linear operators to their standard operator norm. In this paper, we study the continuity of the numerical index under two distinct…

Functional Analysis · Mathematics 2026-03-25 Monika , Tattwamasi Amrutam , Priyadarshi Dey

We prove that the countable product of supercomplete spaces having a countable closed cover consisting of partition-complete subspaces is supercomplete with respect to its metric-fine coreflection. Thus, countable products of…

General Topology · Mathematics 2007-05-23 Aarno Hohti , Miroslav Husek , Jan Pelant

We define a Fr\'echet topology on the space $C^\infty(X)[[\hbar]]$ of formal smooth functions on a symplectic manifold $X$, by constructing a sequence of semi-norms on it. For any star product $\star$ on $C^\infty(X)[[\hbar]]$ making it a…

Quantum Algebra · Mathematics 2026-04-02 Qin Li

Let $D_j\subset\Bbb C^{k_j}$ be a pseudoconvex domain and let $A_j\subset D_j$ be a locally pluripolar set, $j=1,...,N$. Put$$X:=\bigcup_{j=1}^N A_1\times...\times A_{j-1}\times D_j\times A_{j+1}\times...\times A_N\subset\Bbb…

Complex Variables · Mathematics 2007-05-23 Marek Jarnicki , Peter Pflug

We extend a recent result that for the (additive) semigroup of positive integers $\mathbb{N}$, there are continuum many subdirect products of $\mathbb{N} \times \mathbb{N}$ up to isomorphism. We prove that for $U,V$ each one of $\mathbb{Z}$…

Group Theory · Mathematics 2025-01-08 Ashley Clayton , Katie Reilly , Nik Ruskuc

The Stone-Cech compactification of the natural numbers bN, or equivalently, the space of ultrafilters on the subsets of omega, is a well-studied space with interesting properties. If one replaces the subsets of omega by partitions of omega,…

Logic · Mathematics 2007-05-23 Lorenz Halbeisen , Benedikt Loewe

A topological space $X$ is called submaximal if every dense subset of $X$ is open. In this paper, we show that if $\beta X$, the Stone-\v{C}ech compactification of $X$, is a submaximal space, then $X$ is a compact space and hence $\beta…

General Topology · Mathematics 2022-05-17 Rostam Mohamadian

Let $X$ be a real separable normed space $X$ admitting a separating polynomial. We prove that each continuous function from a subset $A$ of $X$ to a real Banach space can be uniformly approximated by restrictions to $A$ of functions which…

Functional Analysis · Mathematics 2020-04-03 M. A. Mytrofanov , A. V. Ravsky

Some zeta functions which are naturally attached to the locally homogeneous vector bundles over compact locally symmetric spaces of rank one are investigated. We prove that such functions can be expressed in terms of entire functions whose…

Number Theory · Mathematics 2016-05-02 M. Avdispahić , Dž. Gušić , D. Kamber

Let $X$ be a normed space of a finite dimension at least two, and $C\subsetneq X$ a closed convex set with nonempty interior. We are interested in extending Lipschitz quasiconvex functions on $C$ to quasiconvex functions on $X$. We show…

Functional Analysis · Mathematics 2026-03-06 Carlo Alberto De Bernardi , Libor Veselý

This paper studies the C-compact-open topology on the set C(X) of all realvalued continuous functions on a Tychonov space X and compares this topology with several well-known and lesser known topologies. We investigate the properties…

General Topology · Mathematics 2012-01-10 Alexander V. Osipov

For realcompact spaces X and Y we give a complete description of the linear biseparating maps between spaces of vector-valued continuous functions on X and Y, where special attention is paid to spaces of vector-valued bounded continuous…

Functional Analysis · Mathematics 2007-05-23 Jesus Araujo

In this paper is considered a problem of defining natural star-products on symplectic manifolds, admissible for quantization of classical Hamiltonian systems. First, a construction of a star-product on a cotangent bundle to an Euclidean…

Mathematical Physics · Physics 2015-06-17 Maciej Blaszak , Ziemowit Domanski

It is proved that for every stratifiable space $Y$ and a closed subset $X\subset Y$ there exists a regular (i.e. linear positive with unit norm) extension operator $T:C(X\times X)\to C(Y\times Y)$ preserving the class of (pseudo)metrics.…

Functional Analysis · Mathematics 2025-11-26 Taras Banakh
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