# Metric geometry

Metric geometry: Rademacher’s theorem in metric measure spaces and Alberti representations.

# Summary

This topics course concerns the study of Rademacher’s differentiation theorem in the setting of general metric spaces. Specifically, we will present a new proof of Cheeger’s celebrated generalisation of Rademacher’s theorem when the domain is replaced with a metric measure space that satisfies a Poincaré inequality.

This proof relies on recently developed techniques in analysis on metric spaces. We will also cover more standard aspects of this theory, in particular Gromov-Hausdorff convergence and weak tangent spaces.

Lecture notes are provided and will be updated throughout the course.

# Exercises

- Exercise 1 deadline 18.09. Ideas for solutions
- Exercise 2 deadline 02.10. Ideas for solutions
- Exercise 3 deadline 16.10. Ideas for solutions
- Exercise 4 deadline 13.11. Ideas for solutions

# Other notes

There are lecture notes from a mini course I gave in Edinburgh.
These contain only the parts of the course that are relevant for the proof of Cheeger’s theorem.
However, there is a significant difference: these notes deal with *curve fragments* in a metric space, rather than (connected) curves.
The benefit of this approach is that it does not require embeddings into a Banach space for the extra structure.
Conceptually, the proof is exactly the same.

There are also lecture notes from a mini course I gave in Jyväskylä.