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Related papers: Countable support iterations and large continuum

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We show that the separative quotient of the poset (P(L),\subset) of isomorphic suborders of a countable scattered linear order L is \sigma-closed and atomless. So, under the CH, all these posets are forcing-equivalent (to P(\omega)/Fin).

Logic · Mathematics 2017-09-26 Milos S. Kurilic

There is a proper countable support iteration of length $\omega$ adding no new reals at finite stages and adding a Sacks real in the limit.

Logic · Mathematics 2011-01-25 Jakob Kellner , Saharon Shelah

I prove preservation theorems for countable support iteration of proper forcing concerning certain classes of capacities and submeasures. New examples of forcing notions and connections with measure theory are included.

Logic · Mathematics 2007-05-23 Jindrich Zapletal

A forcing extension may create new isomorphisms between two models of a first order theory. Certain model theoretic constraints on the theory and other constraints on the forcing can prevent this pathology. A countable first order theory is…

Logic · Mathematics 2016-09-06 John T. Baldwin , Michael C. Laskowski , Saharon Shelah

We prove various iteration theorems for forcing classes related to subproper and subcomplete forcing, introduced by Jensen. In the first part, we use revised countable support iterations, and show that 1) the class of subproper,…

Logic · Mathematics 2025-04-16 Gunter Fuchs , Corey Bacal Switzer

We construct, from a ground model of $ZFC$, a transitive symmetric model $M$ satisfying $ZF + DC + PP + AC_{wo} + \neg AC$. The construction starts with a Cohen symmetric seed model $N$ over $Add(\omega,\omega_1)$ and performs an Ord-length…

Logic · Mathematics 2026-03-10 Frank Gilson

Combining creature forcing approaches from arXiv:1003.3425 and arXiv:1402.0367, we show that, under CH, there is a proper $\omega^\omega$-bounding poset with $\aleph_2$-cc that forces continuum many pairwise different cardinal…

We show that all finite powers of a Hausdorff space X do not contain uncountable weakly separated subspaces iff there is a c.c.c poset P such that 1_P forces that ``X is a countable union of 0-dimensional subspaces of countable weight.'' We…

Logic · Mathematics 2016-09-06 I. Juhász , Lajos Soukup , Z. Szentmiklóssy

We introduce a simplified framework for ord-transitive models and Shelah's non elementary proper (nep) theory. We also introduce a new construction for the countable support nep iteration.

Logic · Mathematics 2015-09-07 Jakob Kellner

Let \alpha be a countable ordinal and \P(\alpha) the collection of its subsets isomorphic to \alpha. We show that the separative quotient of the set \P (\alpha) ordered by the inclusion is isomorphic to a forcing product of iterated reduced…

Logic · Mathematics 2017-09-26 Milos Kurilic

We introduce the idea of a coherent adequate set of models, which can be used as side conditions in forcing. As an application we define a forcing poset which adds a square sequence on $\omega_2$ using finite conditions.

Logic · Mathematics 2014-06-13 John Krueger

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

We develop a toolbox for forcing over arbitrary models of set theory without the axiom of choice. In particular, we introduce a variant of the countable chain condition and prove an iteration theorem that applies to many classical forcings…

Logic · Mathematics 2023-01-02 Daisuke Ikegami , Philipp Schlicht

We state a new generic absoluteness principle, and use Shelah's memory iteration technique to show that it is consistent with the large continuum.

Logic · Mathematics 2023-10-10 Mohammad Golshani

The cardinal invariants $ \mathfrak h, \mathfrak b, \mathfrak s$ of $\mathcal P (\omega)$ are known to satisfy that $\omega_1 \leq \mathfrak h \leq\min\{\mathfrak b, \mathfrak s\}$. We prove that all inequalities can be strict. We also…

Logic · Mathematics 2022-02-02 Alan Dow , Saharon Shelah

This article continues Ros{\l}anowski and Shelah math.LO/9906024, math.LO/0508272, math.LO/0210205, math.LO/0611131 and math.LO/0605067. We introduce here a new property of <lambda-strategically complete forcing notions which implies that…

Logic · Mathematics 2013-08-20 Andrzej Roslanowski , Saharon Shelah

Assuming the Continuum Hypothesis, there is a compact first countable connected space of weight aleph_1 with no totally disconnected perfect subsets. Each such space, however, may be destroyed by some proper forcing order which does not add…

General Topology · Mathematics 2007-05-23 Joan E. Hart , Kenneth Kunen

We present a direct construction of stationary set preserving forcings that make $\omega$-cofinal all the members of some arbitrary set $\mathcal{K}$ of regular cardinals $\kappa > \omega_1$. In addition, it is made possible to ensure that…

Logic · Mathematics 2025-10-29 Ben De Bondt , Boban Velickovic

We develop the theory of the forcing with trees and creatures for an inaccessible lambda continuing Ros{\l}anowski and Shelah math.LO/9807172, math.LO/9909115. To make a real use of these forcing notions (that is to iterate them without…

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

If T has only countably many complete types, yet has a type of infinite multiplicity then there is a ccc forcing notion Q such that, in any Q --generic extension of the universe, there are non-isomorphic models M_1 and M_2 of T that can be…

Logic · Mathematics 2007-05-23 Michael C. Laskowski , Saharon Shelah