Logic Seminar

I will define a class of equivalence relations called Polishable equivalence relations that lies between the class of orbit equivalence relations of Polish group actions and the class of idealistic equivalence relations of Kechris and Louveau. I will present a Scott analysis for such equivalence relations. I will compare this analysis with the Scott analysis for isomorphism equivalence relations from continuous model theory and with versions of the Scott analysis for (certain) orbit equivalence relations of Polish group actions. As a tool in the proofs, I will introduce transfinite filtrations from one topology to another, a new notion of interpolation between topologies that may be of independent interest.