[HTML][HTML] Ideals on countable sets: a survey with questions

C Uzcátegui Aylwin - Revista Integración, 2019 - scielo.org.co
An ideal on a set X is a collection of subsets of X closed under the operations of taking finite
unions and subsets of its elements. Ideals are a very useful notion in topology and set theory …

[HTML][HTML] Analytic P-ideals and Banach spaces

P Borodulin-Nadzieja, B Farkas - Journal of Functional Analysis, 2020 - Elsevier
We study the interplay between Banach space theory and theory of analytic P-ideals.
Applying the observation that, up to isomorphism, all Banach spaces with unconditional …

Regular matrices of unbounded linear operators

P Leonetti - Proceedings of the Royal Society of Edinburgh Section …, 2024 - cambridge.org
Let-convergent (and bounded). This allows us to establish the relationship between the
classical Silverman–Toeplitz characterization of regular matrices and its multidimensional …

[HTML][HTML] Topological representations

A Kwela, M Sabok - Journal of Mathematical Analysis and Applications, 2015 - Elsevier
This paper studies the combinatorics of ideals which recently appeared in ergodicity results
for analytic equivalence relations. The ideals have the following topological representation …

[HTML][HTML] Limit points of subsequences

P Leonetti - Topology and its Applications, 2019 - Elsevier
Let x be a sequence taking values in a separable metric space and let I be an F σ δ-ideal on
the positive integers (in particular, I can be any Erdős–Ulam ideal or any summable ideal). It …

Different kinds of density ideals

J Tryba - Journal of Mathematical Analysis and Applications, 2021 - Elsevier
The paper considers several different kinds of ideals defined by some densities. We depict
relationships between Erdős-Ulam, density, matrix summability and generalized density …

On some locally convex FK spaces

P Leonetti, C Orhan - Topology and its Applications, 2022 - Elsevier
We provide necessary and/or sufficient conditions on vector spaces V of real sequences to
be a Fréchet space such that each coordinate map is continuous, that is, to be a locally …

[HTML][HTML] HL ideals and Sacks indestructible ultrafilters

D Chodounský, O Guzmán, M Hrušák - Annals of Pure and Applied Logic, 2024 - Elsevier
We study ultrafilters on countable sets and reaping families which are indestructible by
Sacks forcing. We deal with the combinatorial characterization of such families and we prove …

On the structure of Borel ideals in-between the ideals ED and Fin⊗ Fin in the Katětov order

P Das, R Filipów, S Gła̧b, J Tryba - Annals of Pure and Applied Logic, 2021 - Elsevier
For a family F⊆ ω ω we define the ideal I (F) on ω× ω to be the ideal generated by the family
{A⊆ ω× ω:∃ f∈ F∀∞ n (|{k:(n, k)∈ A}|≤ f (n))}. Using ideals of the form I (F), we show that …

Strong universality, recurrence, and analytic P-ideals in dynamical systems

P Leonetti - arXiv preprint arXiv:2401.01131, 2024 - arxiv.org
Given a dynamical system $(X, T) $ and a family $\mathsf {I}\subseteq\mathcal {P}(\omega) $
of" small" sets of nonnegative integers, a point $ x\in X $ is said to be $\mathsf {I} $-strong …