Research Interests
In pure mathematics my research has concentrated on function spaces and geometric measure theory. I did much of my early work on bounded analytic functions in planar domains and the space of functions of bounded mean oscillation (BMO) on Euclidean space. I found a constructive method of producing bounded solutions to the d-bar problem when the data was a Carleson measure, and this later led to my proof with John Garnett of the corona problem for Denjoy domains. I also worked on various problems concerning Sobolev spaces, including a proof that locally uniform domains are extension domains for all classical Sobolev spaces. My work in potential theory includes a theorem proven with Tom Wolf: On every planar domain, the harmonic measure is supported on a set of Hausdorff dimension at most one. This extended a result due to N.G. Makarov for the simply connected case. My work in geometric measure theory has centered on results in quantitative rectifiability. I proved that in the plane one can give a geometric multi-scale condition for solving the analyst's traveling salesman problem: When is a set contained in a curve (connected set) of finite length? One half of that proof works in any dimension; the other half was later proven in all dimensions by Kate Okikiolu. With Chris Bishop I proved several results on Hausdorff dimension of limit sets of Kleinian groups. Recently I have been working on problems related to diffusion geometry, a method used for discovery in data sets. With Mauro Maggioni and Raanan Schul I have shown that on Riemannian manifolds with minimal smoothness, one can use eigenfunctions to efficiently put coordinate systems on embedded balls.
Membership Type
Member
Election Year
2008
Primary Section
Section 11: Mathematics
Secondary Section
Section 32: Applied Mathematical Sciences