PFA and the definability of the nonstationary ideal

Stefan Hoffelner, Paul Larson, Ralf Schindler +1

We produce, relative to a $\mathsf{ZFC}$ model with a supercompact cardinal, a $\mathsf{ZFC}$ model of the Proper Forcing Axiom in which the nonstationary ideal on ${\omega }_1$ is ${\Pi }_1$-definab…