6 citations · 15 across the 5 of their papers we have counts for
5 papers
Densities for sets of natural numbers vanishing on a given family
Rafał Filipów, Jacek Tryba
Abstract upper densities are monotone and subadditive functions from the power set of positive integers into the unit real interval that generalize the upper densities used in numb…
New Hindman spaces
Rafał Filipów, Krzysztof Kowitz, Adam Kwela +1
We introduce a method that allows to turn topological questions about Hindman spaces into purely combinatorial questions about the Katětov order of ideals on . We also…
Characterizing existence of certain ultrafilters
Rafał Filipów, Krzysztof Kowitz, Adam Kwela
Following Baumgartner [J. Symb. Log. 60 (1995), no. 2], for an ideal on , we say that an ultrafilter on is an -ultrafilter if for ev…
The ideal test for the divergence of a series
Rafał Filipów, Adam Kwela, Jacek Tryba
We generalize the classical Olivier's theorem which says that for any convergent series with positive nonincreasing real terms the sequence tends to zero. Ou…
On the structure of Borel ideals in-between the ideals and in the Katětov order
Pratulananda Das, Rafał Filipów, Szymon Głąb +1
For a family we define the ideal on to be the ideal generated by the family $\{A\subseteq ω\timesω:\exists f\in \ma…