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pro vyhledávání: '"Niemiec, Piotr"'
Autor:
Niemiec, Piotr
The main aim of the paper is to introduce the concept of metric duality in the category of topological Abelian groups that extends the classical notion of duality for normed vector spaces and behaves quite nicely for LCA groups (equipped with nice me
Externí odkaz:
http://arxiv.org/abs/2406.19924
Autor:
Niemiec, Piotr
The main aim of the paper is to study in greater detail absolutely homogeneous structures (that is, objects with the property that each partial isomorphism extends to a global automorphism), with special emphasis on metric spaces and (possibly infini
Externí odkaz:
http://arxiv.org/abs/2308.09986
Publikováno v:
In Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 5 November 2024 320
Autor:
Błaszczyk, Bartłomiej, Waliszewska-Prosół, Marta, Więckiewicz, Mieszko, Poręba, Rafał, Niemiec, Piotr, Przegrałek, Jakub, Martynowicz, Helena
Publikováno v:
In Sleep Medicine Reviews December 2024 78
Autor:
Niemiec, Piotr
Publikováno v:
Adv. Operator Theory 5 (2020), 950-993
It is shown that a positive (bounded linear) operator on a Hilbert space with trivial kernel is unitarily equivalent to a Hankel operator that satisfies double positivity condition if and only if it is non-invertible and has simple spectrum (that is,
Externí odkaz:
http://arxiv.org/abs/2001.06552
Autor:
Niemiec, Piotr
The aim of the paper is to give a full characterization of functions f from I into the real line R (where I is an interval in R that satisfies certain natural conditions) such that for any I-valued positive definite kernel K defined on an arbitrary s
Externí odkaz:
http://arxiv.org/abs/1912.04340
Akademický článek
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Autor:
Niemiec, Piotr, Pikul, Piotr
Publikováno v:
Math. Slovaca 72 (2022), 165-184
A soft presentation of hyperbolic spaces, free of differential apparatus, is offered. Fifth Euclid's postulate in such spaces is overthrown and, among other things, it is proved that spheres (equipped with great-circle distances) and hyperbolic and E
Externí odkaz:
http://arxiv.org/abs/1801.07609
Autor:
Niemiec, Piotr, Wójcik, Paweł
Publikováno v:
Studia Math. 252 (2020), 27-48
The paper deals with continuous homomorphisms $S \ni s \mapsto T_s \in L(E)$ of amenable semigroups $S$ into the algebra $L(E)$ of all bounded linear operators on a Banach space $E$. For a closed linear subspace $F$ of $E$, sufficient conditions are
Externí odkaz:
http://arxiv.org/abs/1705.08967
Autor:
Niemiec, Piotr
A new category of topological spaces with additional structures, called m-towers, is introduced. It is shown that there is a covariant functor which establishes a one-to-one correspondences between unital (resp. arbitrary) subhomogeneous C*-algebras
Externí odkaz:
http://arxiv.org/abs/1310.5595