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.