Lecture 2: Definable quotient spaces and complex geometry
Abstract: Various quotients of homogeneous spaces by the action of discrete groups play important roles in such subjects as the theory of quadratic forms, the study of modular functions, Hodge theory, and homogeneous dynamics, amongst others. Strictly speaking the map from such a homogeneous space to the quotient cannot be definable in an o-minimal structure, but as various other authors (e.g. Bakker, Klingler, Tsimerman, Peterzil, Starchenko, etc.) have observed, by making suitable restrictions it can be fruitfully analyzed using o-minimality and the quotient spaces themselves may be treated as definable objects. I will discuss how to develop this theory and some basic open questions and will then show how this formalism may be used to prove some general theorems around the Zilber-Pink conjectures. (This is an account of joint work with Jonathan Pila and separately with Sebastian Eterović.)