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Collapsing \(\omega _2\) with semi-proper forcing

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Abstract

We examine the differences between three standard classes of forcing notions relative to the way they collapse the continuum. It turns out that proper and semi-proper posets behave differently in that respect from the class of posets that preserve stationary subsets of \(\omega _1\).

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Authors and Affiliations

  1. Department of Mathematics, University of Toronto, Toronto, Canada

    Stevo Todorcevic

  2. Institut de Mathématiques de Jussieu, Paris, France

    Stevo Todorcevic

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  1. Stevo Todorcevic
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Correspondence to Stevo Todorcevic.

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Research partially supported by grants from NSERC and CNRS.

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Todorcevic, S. Collapsing \(\omega _2\) with semi-proper forcing. Arch. Math. Logic 57, 185–194 (2018). https://doi.org/10.1007/s00153-017-0588-x

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  • DOI: https://doi.org/10.1007/s00153-017-0588-x

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