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Extender based forcings

Published online by Cambridge University Press:  12 March 2014

Moti Gitik
Affiliation:
Sackler Faculty of Exact Sciences, School of Mathematical Sciences, Tel Aviv University, Ramat Aviv 69978, Israel, E-mail: gitik@math.tan.ac.il
Menachem Magidor
Affiliation:
Department of Mathematics, Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel, E-mail: menachem@math.huji.ac.il

Abstract

The paper is a continuation of [The SCH revisited], In § 1 we define a forcing with countably many nice systems. It is used, for example, to construct a model “GCH below κ, c f κ = ℵ0, and 2κ > κ+ω from 0(κ) = κ+ω. In §2 we define a triangle iteration and use it to construct a model satisfying “{μλc f μ = ℵ0 and pp(μ) > λ} is countable for some λ”. The question of whether this is possible was asked by S. Shelah. In §3 a forcing for blowing the power of a singular cardinal without collapsing cardinals or adding new bounded subsets is presented. Answering a question of H. Woodin, we show that it is consistent to have “c f κ = ℵ0. GCH below κ, 2κ > κ+, and ”. In §4 a variation of the forcing of [The SCH revisited, §1] is defined. It behaves nicely in iteration processes. As an application, we sketch a construction of a model satisfying:

κ is a measurable and 2κκ+α for some α, κ < c f α < α” starting with 0(κ) = κ+α. This answers the question from Gitik's On measurable cardinals violating the continuum hypothesis.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1994

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References

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