43 research outputs found
A Pettis-Type Integral and Applications to Transition Semigroups
Motivated by applications to transition semigroups, we introduce the notion
of a norming dual pair and study a Pettis-type integral on such pairs. In
particular, we establish a sufficient condition for integrability. We also
introduce and study a class of semigroups on such dual pairs which are an
abstract version of transition semigroups. Using our results, we give
conditions ensuring that a semigroup consisting of kernel operators has a
Laplace transform which also consists of kernel operators. We also provide
conditions under which a semigroup is uniquely determined by its Laplace
transform.Comment: Incorporated referee's comments; final versio
Adjoint bi-continuous semigroups and semigroups on the space of measures
For a given bi-continuous semigroup T on a Banach space X we define its
adjoint on an appropriate closed subspace X^o of the norm dual X'. Under some
abstract conditions this adjoint semigroup is again bi-continuous with respect
to the weak topology (X^o,X). An application is the following: For K a Polish
space we consider operator semigroups on the space C(K) of bounded, continuous
functions (endowed with the compact-open topology) and on the space M(K) of
bounded Baire measures (endowed with the weak*-topology). We show that
bi-continuous semigroups on M(K) are precisely those that are adjoints of a
bi-continuous semigroups on C(K). We also prove that the class of bi-continuous
semigroups on C(K) with respect to the compact-open topology coincides with the
class of equicontinuous semigroups with respect to the strict topology. In
general, if K is not Polish space this is not the case
A Lie-Trotter product formula for Ornstein-Uhlenbeck semigroups in infinite dimensions
Delft Institute of Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc