The topology of the relative character varieties of a quadruply-punctured sphere.
The virtual Haken conjecture: Experiments and examples.
Three Conjectures of Combinatorial Topology.
Three-manifolds and Kähler groups
We give a simple proof of a result originally due to Dimca and Suciu: a group that is both Kähler and the fundamental group of a closed three-manifold is finite. We also prove that a group that is both the fundamental group of a closed three-manifold and of a non-Kähler compact complex surface is or .
Topological classification of conformal actions on -hyperelliptic Riemann surfaces.
Topological components of spaces of representations.
Topology of arrangements and position of singularities
This work contains an extended version of a course given in Arrangements in Pyrénées. School on hyperplane arrangements and related topics held at Pau (France) in June 2012. In the first part, we recall the computation of the fundamental group of the complement of a line arrangement. In the second part, we deal with characteristic varieties of line arrangements focusing on two aspects: the relationship with the position of the singular points (relative to projective curves of some prescribed degrees)...
Torus knots and Dunwoody manifolds.
Trees of Homotopy Types of Two-Dimensional CW-Complexes
Trees, valuations, and the Bieri-Neumann-Strebel invariant.
Twisted Alexander polynomials and surjectivity of a group homomorphism.