The complexity of non-stationary ideals

Philipp Lücke

Published 2024-04-04Version 1

We present an overview of results on the question of whether the non-stationary ideal of an uncountable regular cardinal $\kappa$ can be defined by a $\Pi_1$-formula using parameters of hereditary cardinality at most $\kappa$. These results show that this question is deeply connected to several central topics of current research in set theory.