Variations of the stick principle
Abstract: The stick principle is a weakening of Jensen's diamond that asserts that there is a family of infinite subsets of $omega_1$ so that any uncountable subset of $\omega_1$ has some member of the family as a subset. We will give a forcing construction to separate versions of the stick principle which put a bound on the order-type of the subsets in the family. Many open problems remain about the relationship between different variations of this principle, such as the existence of certain club-guessing sequences or Suslin trees, and we will describe some progress in this direction.
Tuesday September 26, 2017 at 4:00 PM in SEO 427