Displaying similar documents to “Some results about dissipativity of Kolmogorov operators”

On exit laws for semigroups in weak duality

Imed Bachar (2001)

Commentationes Mathematicae Universitatis Carolinae

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Let : = ( P t ) t > 0 be a measurable semigroup and m a σ -finite positive measure on a Lusin space X . An m -exit law for is a family ( f t ) t > 0 of nonnegative measurable functions on X which are finite m -a.e. and satisfy for each s , t > 0 P s f t = f s + t m -a.e. An excessive function u is said to be in if there exits an m -exit law ( f t ) t > 0 for such that u = 0 f t d t , m -a.e. Let 𝒫 be the cone of m -purely excessive functions with respect to and m V be the cone of m -potential functions. It is clear that m V 𝒫 . In this...

On the range of a closed operator in an L 1 -space of vector-valued functions

Ryotaro Sato (2005)

Commentationes Mathematicae Universitatis Carolinae

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Let X be a reflexive Banach space and A be a closed operator in an L 1 -space of X -valued functions. Then we characterize the range R ( A ) of A as follows. Let 0 λ n ρ ( A ) for all 1 n < , where ρ ( A ) denotes the resolvent set of A , and assume that lim n λ n = 0 and sup n 1 λ n ( λ n - A ) - 1 < . Furthermore, assume that there exists λ ρ ( A ) such that λ ( λ - A ) - 1 1 . Then f R ( A ) is equivalent to sup n 1 ( λ n - A ) - 1 f 1 < . This generalizes Shaw’s result for scalar-valued functions.

Transition semigroups for stochastic semilinear equations on Hilbert spaces

Anna Chojnowska-Michalik

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A large class of stochastic semilinear equations with measurable nonlinear term on a Hilbert space H is considered. Assuming the corresponding nonsymmetric Ornstein-Uhlenbeck process has an invariant measure μ, we prove in the L p ( H , μ ) spaces the existence of a transition semigroup ( P t ) for the equations. Sufficient conditions are provided for hyperboundedness of P t and for the Log Sobolev Inequality to hold; and in the case of a bounded nonlinear term, sufficient and necessary conditions are obtained....