I sometimes write posts on the Low-dimensional topology blog. My posts so far are as follows.
- When are two hyperbolic 3-manifolds homeomorphic?
- ... or Agol's Theorem?
- Wise's Conjecture
- Mineyev and the Hanna Neumann Conjecture
- Virtually geometric words
- Homogeneous hyperbolic groups
- 3-manifold groups are known, right?
- Call for Tricki articles
- Surfaces in hyperbolic groups
- A course on Geometric Group Theory
- In Memoriam J. R. Stallings - Topology of Finite Graphs
Here are the notes, blogged by the students, for a course that I taught in the Spring semester of 2009 at the University of Texas.
- Non-positively curved cube complexes. These are the notes for a course that I taught in the Winter term of 2011 at Caltech.
- In the autumn of 2007 I visited the MSRI for their Geometric Group Theory programme. Lars Louder and I took notes on Zlil Sela's course on definable sets in free groups. In their current, incomplete state they can be found here.
- My notes on the Rips machine, closely based on Misha Kapovich's book.
- My Part III essay on The Geometrization Conjecture
Here are the slides or any other online records of some of the talks that I've given. E-mails pointing out typos and other errors are appreciated.
- One-ended subgroups of graphs of free groups (Group Theory International Webinar, January 2011)
- Computing solutions to systems of equations over free and hyperbolic groups (AMS Sectional Meeting, Baton Rouge, March 2008; Groups and Dynamics Seminar, Texas A&M, March 2008)
- Subgroup separability in residually free groups (Introduction to Geometric Group Theory, MSRI, Berkeley, August 2008), visible online here
- Some residual properties of groups (AMS Sectional Meeting, University of Utah, October 2006)
- Limit groups, measure equivalence and subgroup separability (Geometry, Integrable Systems and Topology, University of Glasgow, January 2006)
- Subgroup separability and limit groups (London Algebra Colloquium, November 2005)
- An Introduction to Limit Groups (Series for Telgiggy, Imperial College, London, January 2005)
I also have notes/slides for graduate talks on An Introduction to Geometrization, Group actions on trees, Algebraic geometry over groups, Bass-Serre theory and Hyperbolic spaces, R-trees and outer automorphisms.