LOGIC SEMINAR, Thursday October 2
SPEAKER: Anand Pillay (UIUC)
TITLE: Hyperimaginaries, canonical bases, compact groups
ABSTRACT: I discuss a generalisation of "imaginary" elements in model theory to "hyperimaginaries" (equivalence classes of type-definable equivalence relations on possibly infinite tuples), and how they can be dealt with within ordinary first order logic. I will mention their role in finding canonical bases for (families) of types in simple theories. I will also discuss how the structure theory for compact groups allows us to eliminate "infinitary bounded hyperimaginaries" in favour of "finitary bounded hyperimaginaries" under some general hypotheses.