Archive for Mathematical Logic

, Volume 57, Issue 1–2, pp 185–194 | Cite as

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

  • Stevo TodorcevicEmail author


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 \(\omega _1\).


Oscillation Forcing Stationary set 

Mathematics Subject Classification

Primary 03E20 


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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  1. 1.Department of MathematicsUniversity of TorontoTorontoCanada
  2. 2.Institut de Mathématiques de JussieuParisFrance

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