Mathematical logic seminar – Apr 11 2017
Time: 3:30pm – 4:30 pm
Room: Wean Hall 8220
Speaker: James Cummings
Department of Mathematical Sciences
Title: Definable subsets of singular cardinals
Shelah proved the surprising result that if μ is a singular strong limit cardinal of uncountable cofinality, then there is a subset X of μ such that all subsets of μ are ordinal-definable from X. We will give a proof and discuss some complementary consistency results.