Stationary Reflection and the failure of SCH
Speaker:
Spencer Unger, University of California, Los Angeles
Date and Time:
Friday, January 17, 2020 - 10:00am to 11:30am
Location:
Fields Institute, Room 210
Abstract:
We prove that from large cardinals it is consistent that there is a singular strong limit cardinal $\nu$ such that the singular cardinal hypothesis fails at $\nu$ and every collection of fewer than $\mathrm{cf}(\nu)$ stationary subsets of $\nu^+$ reflects simultaneously. For uncountable cofinality, this situation was not previously known to be consistent. Using different methods, we reduce the upper bound on the consistency strength of this situation for $\mathrm{cf}(\nu)=\omega$ to below a single partially supercompact cardinal. The previous upper bound of infinitely many supercompact cardinals was due to Sharon. Joint work with Omer Ben-Neria and Yair Hayut.