Necessary and sufficient conditions for hypoelliptic of certain left invariant operators on nilpotent Lie groups II.
New smooth disintegration of for exponential solvable groups. (Nouvelle désintégration lisse de pour les groupes résolubles exponentiels.)
Noncolliding Brownian motions and Harish-Chandra formula.
Nonlinear potential theory for Sobolev spaces on Carnot groups.
Nonlocal Poincaré inequalities on Lie groups with polynomial volume growth and Riemannian manifolds
Let G be a real connected Lie group with polynomial volume growth endowed with its Haar measuredx. Given a C² positive bounded integrable function M on G, we give a sufficient condition for an L² Poincaré inequality with respect to the measure M(x)dx to hold on G. We then establish a nonlocal Poincaré inequality on G with respect to M(x)dx. We also give analogous Poincaré inequalities on Riemannian manifolds and deal with the case of Hardy inequalities.
Note on analytic regularity of heat kernels on nilpotent Lie groups
Let G be the simplest nilpotent Lie group of step 3. We prove that the densities of the semigroup generated by the sublaplacian on G are not real-analytic.
Note on coarea formulae in the Heisenberg group.
We show a first nontrivial example of coarea formula for vector-valued Lipschitz maps defined on the three dimensional Heisenberg group. In this coarea formula, integration on level sets is performed with respect to the 2-dimensional spherical Hausdorff measure, built by the Carnot-Carathéodory distance. The standard jacobian is replaced by the so called horizontal jacobian, corresponding to the jacobian of the Pansu differential of the Lipschitz map. Joining previous results, we achieve all possible...
Note on semigroups generated by positive Rockland operators on graded homogeneous groups
Let L be a positive Rockland operator of homogeneous degree d on a graded homogeneous group G and let be the convolution kernels of the semigroup generated by L. We prove that if τ(x) is a Riemannian distance of x from the unit element, then there are constants c>0 and C such that . Moreover, if G is not stratified, more precise estimates of at infinity are given.