Ernest Schimmerling

Mathematical logic seminar - October 9, 2002

Speaker: John Krueger
Graduate Student
Department of Mathematical Sciences
Carnegie Mellon University

Title: Destroying stationary sets, part I


I will discuss a new forcing technique which I developed for destroying the stationarity of subsets of

$P_\kappa \kappa^+ = \{ a \subseteq \kappa^+ : |a| < \kappa \}$
where $\kappa$ is weakly inaccessible. In order to destroy one stationary set while preserving the stationarity of another, it is necessary to "prepare" the ground model with a forcing iteration. However since the posets are not closed, the usual Easton support iteration does not work. Instead we use Gitik's Easton support Prikry iteration. I will describe these techniques and some of the problems which I solved using them.