Title: Hyperbolic spaces and their Gromov boundary

Abstract: Hyperbolic spaces defined by Gromov generalize the notion of negative curvature of Riemannian manifolds. This notion turned out to be very useful to study the properties of groups via geometry. In this introductory lecture, I will explain basics of hyperbolic spaces and their Gromov boundary.

Title: Hyperfinite equivalence relations in geometric group theory

Abstract: The classification problem (i.e. classifying mathematical objects) is a fundamental question ubiquitous in all areas of mathematics. A naive approach to this problem is to try to find a complete invariant. However, such an invariant is not always accessible in a well described way. Descriptive set theory provides notions and formulations to measure complexities of classification problems even in such cases. I will...

Speaker: Palle Jorgensen, Dept. of Mathematics

Title: Conditional Positive Definiteness and Complete Monotonicity in Subnormal Operator Theory