Fast intersection methods for the solution of some nonlinear systems of equations.
Finite element approximation of a model reaction - diffusion problem with a non-Lipschitz nonlinearity.
Finite Element Solution of Nonlinear Elliptic Problems.
Free systems of vector fields (d'après L. Hörmander et A. Melin)
Frequency functions on the Heisenberg group, the uncertainty principle and unique continuation
A recent result of Bahouri shows that continuation from an open set fails in general for solutions of where and is a (nonelliptic) operator in satisfying Hörmander’s condition for hypoellipticity. In this paper we study the model case when is the subelliptic Laplacian on the Heisenberg group and is a zero order term which is allowed to be unbounded. We provide a sufficient condition, involving a first order differential inequality, for nontrivial solutions of to have a finite order...
Fundamental solutions and geometry of the sum of squares of vector fields.
Funktionalungleichungen und Iterationsverfahren.