-uniqueness for infinite dimensional symmetric Kolmogorov operators : the case of variable diffusion coefficients
On introduit les espaces fonctionnels dans lesquels l’opérateur potentiel satisfait au principe semi-complet du maximum si et seulement si la contraction module opère. Un tel espace fonctionnel sur la frontière de Martin d’un espace harmonique symétrique de Brelot est envisagé à l’aide du noyau de Naïm. Il est isomorphe à l’espace de Dirichlet des fonctions harmoniques. L’opérateur potentiel de cet espace donne la solution du problème de Neumann. On introduit l’espace de Dirichlet des fonctions...
This paper gives a stochastic representation in spectral terms for the absorption time T of a finite Markov chain which is irreducible and reversible outside the absorbing point. This yields quantitative informations on the parameters of a similar representation due to O'Cinneide for general chains admitting real eigenvalues. In the discrete time setting, if the underlying Dirichlet eigenvalues (namely the eigenvalues of the Markov transition operator restricted to the functions vanishing on...
We show that, if a certain Sobolev inequality holds, then a scale-invariant elliptic Harnack inequality suffices to imply its a priori stronger parabolic counterpart. Neither the relative Sobolev inequality nor the elliptic Harnack inequality alone suffices to imply the parabolic Harnack inequality in question; both are necessary conditions. As an application, we show the equivalence between parabolic Harnack inequality for on , (i.e., for ) and elliptic Harnack inequality for on .
A general representation theorem is obtained for positive quadratic forms, defined on (the space of continuously differentiable functions with compact support contained in ) which are local and on which all normal contractions operate.