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Using a finite support iteration of ccc forcings, we construct a model of $\aleph_1<\mathrm{add}(\mathcal{N})<\mathrm{cov}(\mathcal{N})<\mathfrak{b}<\mathrm{non}(\mathcal{M})<\mathrm{cov}(\mathcal{M})=\mathfrak{c}$.

Logic · Mathematics 2016-07-07 Martin Goldstern , Diego A. Mejía , Saharon Shelah

We develop a new method for building forcing iterations with symmetric systems of structures as side conditions. Using our method we prove that the forcing axiom for the class of all the small finitely proper posets is compatible with a…

Logic · Mathematics 2015-01-26 David Asperó , Miguel Angel Mota

We deal with an iteration theorem of forcing notion with a kind of countable support of nice enough forcing notion which is proper aleph_2-c.c. forcing notions. We then look at some special cases (Q_D 's preceded by random forcing).

Logic · Mathematics 2007-05-23 Saharon Shelah

In this article, we conduct a detailed study of \emph{finitely additive measures} (fams) in the context of Boolean algebras, focusing on three specific topics: freeness and approximation, existence and extension criteria, and integration…

Logic · Mathematics 2025-12-15 Miguel A. Cardona , Diego A. Mejía , Andrés F. Uribe-Zapata

We prove the following theorem: For a partially ordered set Q such that every countable subset has a strict upper bound, there is a forcing notion satisfying ccc such that, in the forcing model, there is a basis of the meager ideal of the…

Logic · Mathematics 2007-05-23 Tomek Bartoszynski , Masaru Kada

We answer a question of Moore by building a forcing extension satisfying measuring together with CH. The construction works over any model of ZFC and can be described as a forcing iteration with countable structures as side conditions and…

Logic · Mathematics 2011-11-14 David Asperó , Miguel Angel Mota

Vladimir Kanovei \cite{zbMATH01335192} developed the technique of geometric iteration and used it to prove that the perfect set forcing can be iterated with countable supports along any partial order, while preserving $\aleph_1$. In…

Logic · Mathematics 2026-04-14 Mirna Džamonja

A central theme in set theory is to find universes with extreme, well-understood behaviour. The case we are interested in is assuming GCH and has a strong forcing axiom of higher order than usual. Instead of "for every suitable forcing…

Logic · Mathematics 2022-03-02 Noam Greenberg , Saharon Shelah

We study relationships between various set theoretic compactness principles, focusing on the interplay between the three families of combinatorial objects or principles mentioned in the title. Specifically, we show the following. (1) Strong…

Logic · Mathematics 2024-01-30 Chris Lambie-Hanson , Assaf Rinot , Jing Zhang

The generic chaining method provides a sharp description of the suprema of many random processes in terms of the geometry of their index sets. The chaining functionals that arise in this theory are however notoriously difficult to control…

Probability · Mathematics 2018-06-22 Ramon van Handel

We present a systematic study of the method of "norms on possibilities" of building forcing notions with keeping their properties under full control. This technique allows us to answer several open problems, but on our way to get the…

Logic · Mathematics 2013-01-03 Andrzej Roslanowski , Saharon Shelah

In this work we present iterated function systems with general measures(IFSm) formed by a set of maps $\tau_{\lambda}$ acting over a compact space $X$, for a compact space of indices, $\Lambda$. The Markov process $Z_k$ associated to the…

Dynamical Systems · Mathematics 2025-05-15 Elismar R. Oliveira , Rafael R. Souza

The notion of forcing sets for perfect matchings was introduced by Harary, Klein, and \v{Z}ivkovi\'{c}. The application of this problem in chemistry, as well as its interesting theoretical aspects, made this subject very active. In this…

Combinatorics · Mathematics 2025-03-04 Javad B. Ebrahimi , Babak Ghanbari

We define typical forcings encompassing many informal forcing arguments in bounded arithmetic and give general conditions for such forcings to produce models of the universal variant of relativized $T^1_2$. We apply this result to study the…

Logic · Mathematics 2020-12-17 Moritz Müller

This is an overview about a method of constructing ccc forcings: Suppose first that a continuous, commutative system of complete embeddings between countable forcings indexed along $\omega_1$ is given. Then its direct limit satisfies ccc by…

Logic · Mathematics 2008-11-07 Bernhard Irrgang

The technique of symmetric extensions is derived from forcing and it is one of the most important tools for studying models without the Axiom of Choice. Despite being incredibly successful since the 1960s, our understanding of the technique…

Logic · Mathematics 2026-02-20 Asaf Karagila , Jonathan Schilhan

We give an exposition of an iteration theorem for iterating $(<\lambda)$-closed stationary $\lambda^+$-cc forcing with supports of size $<\lambda$ and preserving these two properties. We discuss the relation of this theorem with other…

Logic · Mathematics 2026-04-14 Mirna Džamonja

We present a method to iterate finitely splitting lim-sup tree forcings along non-wellfounded linear orders. We apply this method to construct a forcing (without using an inaccessible or amalgamation) that makes all definable sets of reals…

Logic · Mathematics 2011-10-18 Jakob Kellner , Saharon Shelah

Let $\mathcal{F}=\{F_1,F_2, \ldots,F_n\}$ be a family of $n$ sets on a ground set $S$, such as a family of balls in $\mathbb{R}^d$. For every finite measure $\mu$ on $S$, such that the sets of $\mathcal{F}$ are measurable, the classical…

Combinatorics · Mathematics 2014-04-18 Xavier Goaoc , Jiří Matoušek , Pavel Paták , Zuzana Safernová , Martin Tancer

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