Champs de Yang et Mills variés
Complex characteristic coordinates and tangential Cauchy-Riemann equations
Conditions d’unicité pour le propagateur du champ scalaire dans l’univers de de Sitter
Conformal transformations in superspace
Conformally covariant field equations
Construction of Sobolev spaces of fractional order with sub-riemannian vector fields
Given a smooth family of vector fields satisfying Chow-Hörmander’s condition of step 2 and a regularity assumption, we prove that the Sobolev spaces of fractional order constructed by the standard functional analysis can actually be “computed” with a simple formula involving the sub-riemannian distance.Our approach relies on a microlocal analysis of translation operators in an anisotropic context. It also involves classical estimates of the heat-kernel associated to the sub-elliptic Laplacian.
Convergence and accuracy of approximation methods in general relativity. The time-independent case
CR geometry and Cartan geometry.