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Let $\mathcal{E}$ be the ideal generated by the $F_\sigma$ measure zero subsets of the reals. The purpose of this survey paper is to study the cardinal characteristics (the additivity, covering number, uniformity, and cofinality) of…

Logic · Mathematics 2024-02-15 Miguel A. Cardona

Let $\mathcal{SN}$ be the $\sigma$-ideal of the strong measure zero sets of reals. We present general properties of forcing notions that allow to control of the additivity of $\mathcal{SN}$ after finite support iterations. This is applied…

Logic · Mathematics 2025-08-21 Jörg Brendle , Miguel A. Cardona , Diego A. Mejía

We construct models, by three-dimensional arrays of ccc posets, where many classical cardinal characteristics of the continuum are pairwise different.

Logic · Mathematics 2020-07-07 Diego Alejandro Mejía

Let $\mathcal{N}$ be the $\sigma$-ideal of the null sets of reals. We introduce a new property of forcing notions that enable control of the additivity of $\mathcal{N}$ after finite support iterations. This is applied to answer some open…

Logic · Mathematics 2025-02-05 Miguel A. Cardona , Miroslav Repický , Saharon Shelah

Yorioka [J. Symbolic Logic 67(4):1373-1384, 2002] introduced a class of ideals (parametrized by reals) on the Cantor space to prove that the relation between the size of the continuum and the cofinality of the strong measure zero ideal on…

Logic · Mathematics 2020-07-07 Miguel A. Cardona , Diego A. Mejía

Using matrix iterations of ccc posets, we prove the consistency with ZFC of some cases where the cardinals on the right hand side of Cichon's diagram take two or three arbitrary values (two regular values, the third one with uncountable…

Logic · Mathematics 2013-08-12 Diego Alejandro Mejía

For a free ultrafilter U on omega we study several cardinal characteristics which describe part of the combinatorial structure of U. We provide various consistency results; e.g. we show how to force simultaneously many characters and many…

Logic · Mathematics 2016-09-07 Jörg Brendle , Saharon Shelah

Using a countable support product of creature forcing posets, we show that consistently, for uncountably many different functions the associated Yorioka ideals' uniformity numbers can be pairwise different. In addition we show that, in the…

Logic · Mathematics 2022-07-25 Lukas Daniel Klausner , Diego Alejandro Mejía

In their recent paper on posets with a pseudocomplementation denoted by * the first and the third author introduced the concept of a *-ideal. This concept is in fact an extension of a similar concept introduced in distributive…

Rings and Algebras · Mathematics 2022-08-03 Ivan Chajda , Miroslav Kolařík , Helmut Länger

A ccc-generically supercompact cardinal $\kappa$ can be smaller than or equal to the continuum. On the other hand, such a cardinal $\kappa$ still satisfies diverse largeness properties, like that it is a stationary limit of ccc-generically…

Logic · Mathematics 2022-02-17 Sakaé Fuchino , Hiroshi Sakai

Using GCH, we force the following: There are continuum many simple cardinal characteristics with pairwise different values.

Logic · Mathematics 2011-01-25 Jakob Kellner

We introduce the property ``$F$-linked'' of subsets of posets for a given free filter $F$ on the natural numbers, and define the properties ``$\mu$-$F$-linked'' and ``$\theta$-$F$-Knaster'' for posets in a natural way. We show that…

Logic · Mathematics 2020-07-07 Jörg Brendle , Miguel A. Cardona , Diego A. Mejía

We introduce a two-parameter modification of the cofinality invariant of ideals. This allows us to include the interaction of a pair of ideals in the study of base-like structures. We find the values (cardinal numbers or well-known cardinal…

General Topology · Mathematics 2025-02-13 Adam Marton , Miroslav Repický

Let $\mathcal{SN}$ be the strong measure zero $\sigma$-ideal. We prove a result providing bounds for $\mathrm{cof}(\mathcal{SN})$ which implies Yorioka's characterization of the cofinality of the strong measure zero. In addition, we use…

Logic · Mathematics 2020-03-19 Miguel A. Cardona

Inspired by Bartoszy\'nski's work on small sets, we introduce a new ideal defined by interval partitions on natural numbers and summable sequences of positive reals. Similarly, we present another ideal that relies on Bartoszy\'nski's and…

Logic · Mathematics 2025-02-13 Miguel A. Cardona , Adam Marton , Jaroslav Supina

We show that many large cardinal notions up to measurability can be characterized through the existence of certain filters for small models of set theory. This correspondence will allow us to obtain a canonical way in which to assign ideals…

Logic · Mathematics 2021-12-09 Peter Holy , Philipp Lücke

Normal ideals on regular uncountable cardinals are familiar objects. We investigate ideals that are pleasant--while a normal ideal is closed under arbitrary diagonal unions, a pleasant ideal is closed only under diagonal unions indexed by…

Logic · Mathematics 2009-09-25 Christopher Leary

We develop the theory of cofinal types of ultrafilters over measurable cardinals and establish its connections to Galvin's property. We generalize fundamental results from the countable to the uncountable, but often in surprisingly…

Logic · Mathematics 2026-02-11 Tom Benhamou , Natasha Dobrinen

We present a version with non-definable forcing notions of Shelah's theory of iterated forcing along a template. Our main result, as an application, is that, if $\kappa$ is a measurable cardinal and $\theta<\kappa<\mu<\lambda$ are…

Logic · Mathematics 2015-06-23 Diego Alejandro Mejía

This paper provides an extensive study of the $\mathscr{I}$-Miller null ideals $M_\mathscr{I}$, $\sigma$-ideals on the Baire space parametrized by ideals $\mathscr{I}$ on countable sets. These $\sigma$-ideals are associated to the idealized…

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