My research work utilizes concepts from pseudodifferential operators, index theory and non-commutative geometry in the construction of representations of geometric semigroups and categories whose characters define invariants of the background manifold. The character of the index bundle associated to a family of Dirac operators over a Riemann suraface, for example, can be used to enumerate holomorphic maps from the surface into complex projective space, while for manifolds with boundary the characters are connected to gauge groups reoresentations constructed using Grassmannians of elliptic boundary conditions for Dirac operators; this is closely tied in with ideas from quantum and conformal field theory.

Traces of fourier integral operators; geometric analysis; geometry; lie theory.