Piotr Borodulin-Nadzieja

activity

20112026

collaborators

14 papers

math.FA2026

Geometric duality, perfect graphs, and the Sierpiński space

Piotr Borodulin-Nadzieja, Barnabás Farkas, Anna Pelczar-Barwacz

In their classical paper \emph{On the stopping time Banach space}, Bang and Odell, among a plethora of results concerning the dyadic stopping time space and its dual, presented the…

math.LO2025

On the Rudin-Blass Ordering of Measures

Piotr Borodulin-Nadzieja, Arturo Martínez-Celis, Adam Morawski +1

We study the Rudin-Blass (and the Rudin-Keisler) ordering on the finite additive measures on $ω$ . We propose a generalization of the notion of Q-point and selective ultrafilter to…

math.FA2024

The ZOO of combinatorial Banach spaces

Piotr Borodulin-Nadzieja, Barnabás Farkas, Sebastian Jachimek +1

We study Banach spaces induced by families of finite sets in the most natural (Schreier-like) way, that is, we consider the completion $X_\mc{F}$ of $c_{00}$ with respect to the no…

math.LO2024

P-measures in models without P-points

Piotr Borodulin-Nadzieja, Jonathan Cancino-Manríquez, Adam Morawski

We answer in negative the problem if the existence of a P-measure implies the existence of a P-point. Namely, we show that if we add random reals to a certain unique P-point model,…

math.LO2023

On points avoiding measures

Piotr Borodulin-Nadzieja, Artsiom Ranchynski

We say that an element $x$ of a topological space $X$ avoids measures if for every Borel measure $μ$ on $X$ if $μ ({x}) = 0$ , then there is an open $U ∋ x$ such that $μ (U) = 0$ . The…

math.LO2022

There is a P-measure in the random model

Piotr Borodulin-Nadzieja, Damian Sobota

We say that a finitely additive probability measure $μ$ on $ω$ is \emph{a P-measure} if it vanishes on points and for each decreasing sequence $(E_{n})$ of infinite subsets of $ω$ th…