26 citations · 32 across the 11 of their papers we have counts for
6 papers · 1 filter
When surjectivity demands pathology
Piotr Kasprzak, Piotr Maćkowiak
In this paper, we characterize surjective nonlinear composition operators acting between the space of sequences of bounded variation and the space of bounded sequences. We show tha…
On the independence of axioms for measures of non-compactness
Jerzy Grzybowski, Piotr Kasprzak, Piotr Maćkowiak
We investigate the independence of the axioms in the Banaś--Goebel approach to the theory of measures of non-compactness. We present a complete answer for four of the five axioms.…
Integral operators in the spaces of functions of bounded Schramm variation
Jacek Gulgowski, Piotr Kasprzak, Piotr Maćkowiak
In this paper we provide a full characterization of linear integral operators acting from the space of functions of bounded Jordan variation to the space of functions of bounded Sc…
Compactness in Lipschitz spaces and around
Jacek Gulgowski, Piotr Kasprzak, Piotr Maćkowiak
The aim of the paper is to characterize (pre)compactness in the spaces of Lipschitz/Hölder continuous mappings acting from a compact metric space to a normed space. To this end som…
Compactness in normed spaces: a unified approach through semi-norms
Jacek Gulgowski, Piotr Kasprzak, Piotr Maćkowiak
In this paper we prove two new abstract compactness criteria in normed spaces. To this end we first introduce the notion of an equinormed set using a suitable family of semi-norms…
A converse of the Banach contraction principle for partial metric spaces and the continuum hypothesis
Piotr Maćkowiak
A version of the Bessaga inverse of the Banach contraction principle for partial metric spaces is presented. Equivalence of that version and the continuum hypothesis is shown as we…