Generalizations of small cancellation theory

Conjugacy growth functions

Quasi-cocycles, bounded cohomology and stable commutator length

Asymptotic cones

Transitivity degrees and highly transitive actions

The elementary/universal theory of groups and equations in groups

Limit groups and Makanin-Razborov diagrams

Descriptive set theory and the space of marked groups

My papers can be found on the arXiv