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Semiproper forcing axiom implies Martin maximum but not PFA+

Published online by Cambridge University Press:  12 March 2014

Saharon Shelah
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
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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
Information
The Journal of Symbolic Logic , Volume 52 , Issue 2 , June 1987 , pp. 360 - 367
Copyright
Copyright © Association for Symbolic Logic 1987

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References

REFERENCES

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