论文信息 - Semiproper Forcing Axiom Implies Martin Maximum but Not PFA+

Semiproper Forcing Axiom Implies Martin Maximum but Not PFA+

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).

Saharon Shelah

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