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Semiproper forcing axiom implies Martin maximum but not PFA+

Published online by Cambridge University Press:  12 March 2014

Saharon Shelah*
Affiliation:
Department of Mathematics, University of Michigan, Ann Arbor, Michigan 48109 Department of Mathematics, Rutgers University, New Brunswick, New Jersey 08903
*
Institute of Mathematics, The Hebrew University, Jerusalem, Israel

Abstract

We prove that MM (Martin maximum) is equivalent (in ZFC) to the older axiom SPFA (semiproper forcing axiom). We also prove that SPFA does not imply SPFA+ or even PFA+ (using the consistency of a large cardinal).

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1987

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References

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