The bounds for the squared norm of the second fundamental form of minimal submanifolds of .
The Differential Form Spectrum of Hyperbolic Space.
The first eigenvalue of a Riemann surface.
The Laplace-Beltrami operator in almost-Riemannian Geometry
We study the Laplace-Beltrami operator of generalized Riemannian structures on orientable surfaces for which a local orthonormal frame is given by a pair of vector fields that can become collinear.Under the assumption that the structure is 2-step Lie bracket generating, we prove that the Laplace-Beltrami operator is essentially self-adjoint and has discrete spectrum. As a consequence, a quantum particle cannot cross the singular set (i.e., the set where the vector fields become collinear) and the...
The spectrum of the Laplace operator for a spherical space form
Si determina lo spettro di un operatore di Laplace di una «spherical space form» e si studia l’influenza di tale spettro su .
Transition operators on co-compact G-spaces.
We develop methods for studying transition operators on metric spaces that are invariant under a co-compact group which acts properly. A basic requirement is a decomposition of such operators with respect to the group orbits. We then introduce reduced transition operators on the compact factor space whose norms and spectral radii are upper bounds for the Lp-norms and spectral radii of the original operator. If the group is amenable then the spectral radii of the original and reduced operators coincide,...
Transplantation et isospectralité. I.