• Nonnegative curvature
• Nonpositive curvature
• Geometric group theory
• Global Riemannian geometry
• Hyperbolic manifolds and Kleinian groups (including higher dimensions and complex hyperbolic geometry)
• Geometric structures and varieties of representations (hyperbolic, flat conformal, CR, affine structures)
• Topology of manifolds (low-dimensional manifolds, aspherical manifolds, controlled topology)
• Asymptotic (also called large scale) geometry.

Papers:

• Conformally flat Seifert manifolds, Siberian Advances in Math 3 (1993), no. 1, 1-18. MR94i:57022. This paper is available upon request. [Abstract.dvi] [Abstract.ps]
• Some curious Kleinian groups and hyperbolic 5-manifolds, Transformation Groups Vol.2, No.1, 1997, pp. 3-29. [Abstruct] [.dvi] [.ps]
• Discrete surface group actions with accidental parabolics on complex hyperbolic plane, preprint. [Abstract] [.dvi] [.ps]
• Intersections in hyperbolic manifolds, Geometry and Topology, 1998, Vol 2, pp.117-144, electronic: http://www.maths.warwick.ac.uk/gt/
  [Abstract] [.dvi] [.ps]
• Lipschitz precompactness for closed negatively curved manifolds, Proc. Amer. Math. Soc. 127 (1999), pp. 1201-1208. [Abstract] [.dvi] [.ps]
• Counting open negatively curved manifolds up to tangential homotopy equivalence, J. Diff. Geom., 50 (1998) pp. 59-88. [Abstract] [.dvi] [.ps]
• Counting negatively curved manifolds , PhD thesis defended at the University of Maryland, College Park, 1998. [Abstract] [.dvi] [.ps]

Some of my more recent papers can be found at the xxx-preprint archive by clicking here.