Remarques sur la conjecture de Weyl
Let be a complete noncompact manifold of dimension at least 3 and an asymptotically conic metric on , in the sense that compactifies to a manifold with boundary so that becomes a scattering metric on . We study the resolvent kernel and Riesz transform of the operator , where is the positive Laplacian associated to and is a real potential function smooth on and vanishing at the boundary.In our first paper we assumed that has neither zero modes nor a zero-resonance and showed...
We study the Riesz means for the eigenfunction expansions of a class of hypoelliptic differential operators on the Heisenberg group. The operators we consider are homogeneous with respect to dilations and invariant under the action of the unitary group. We obtain convergence results in norm, at Lebesgue points and almost everywhere. We also prove localization results.
We show that the boundedness, p > 2, of the Riesz transform on a complete non-compact Riemannian manifold with upper and lower Gaussian heat kernel estimates is equivalent to a certain form of Sobolev inequality. We also characterize in such terms the heat kernel gradient upper estimate on manifolds with polynomial growth.
Let be a metric space, equipped with a Borel measure satisfying suitable compatibility conditions. An amalgam is a space which looks locally like but globally like . We consider the case where the measure of the ball with centre and radius behaves like a polynomial in , and consider the mapping properties between amalgams of kernel operators where the kernel behaves like when and like when . As an application, we describe Hardy–Littlewood–Sobolev type regularity theorems...
We study the validity of the inequality for the Riesz transform when and of its reverse inequality when on complete riemannian manifolds under the doubling property and some Poincaré inequalities.