-symmetries and reduction of equations without Lie point symmetries.
Circular symmetry and the trace formula.
Classification of differential invariant submodels.
Classification of Monge-Ampère equations with two variables
This paper deals with the classification of hyperbolic Monge-Ampère equations on a two-dimensional manifold. We solve the local equivalence problem with respect to the contact transformation group assuming that the equation is of general position nondegenerate type. As an application we formulate a new method of finding symmetries. This together with previous author's results allows to state the solution of the classical S. Lie equivalence problem for the Monge-Ampère equations.
Comportement asymptotique des valeurs propres du laplacien sur un ouvert à bord fractal
Conservation laws for equations related to soil water equations.
Contact geometry of hyperbolic equations of generic type.
Contact geometry of hyperbolic Monge-Ampére equations.
Convexity for invariant differential operators on semisimple symmetric spaces
Crochet de Jacobi non local sur un revêtement et ses applications à l’étude de l’équation de Burgers
Curved Casimir operators and the BGG machinery.