PREPRINTS (.ps or .pdf)

      The refractor problem in Reshaping light beams, (with Qingbo Huang), Archive for Rational Mechanics and Analysis, to appear.

      Covering theorems, inequalities on metric spaces and applications to pde's, (with G. Di Fazio and E. Lanconelli), Mathematische Annalen, to appear.

      On Monge-Ampere type equations arising in optimal transportation problems, (with T. Van Nguyen), Calculus of Variations and PDEs, to appear.

      On the regularity of reflector antennas, (with L. A. Caffarelli and Qingbo Huang), Annals of Mathematics, to appear.

      Homogenization and convergence of correctors in Carnot groups, (with B. Franchi and T. Van Nguyen), Comm. Partial Differential Equations, to appear.

      W2p estimates for the linearized Monge-Ampere equation, (with F. Tournier), Trans. Amer. Math. Soc., to appear.

      On the second order derivatives of convex functions on the Heisenberg group, (with A. Montanari), Ann. Scuola Norm. Sup. Pisa Cl. Sci., to appear.

      Maximum and comparison principles for convex functions on the Heisenberg group, (with A. Montanari), Comm. Partial Differential Equations, to appear.

      Homogenization of Quasilinear Parabolic Equations in Periodic Media, (with J. Garcia--Azorero, and I. Peral), Comm. Partial Differential Equations, to appear.

      Maximum principle, Harnack inequality, and Liouville theorems for X--elliptic operators, (with E. Lanconelli), Comm. Partial Differential Equations, to appear.

      Regularity of weak solutions to the Monge-Amp\`ere equation, (with D. Hartenstine), Trans. Amer. Math. Soc.