International Journal of Mathematics and Mathematical Sciences
Volume 2004 (2004), Issue 45, Pages 2401-2422
doi:10.1155/S0161171204311105
Abstract
Necessary and sufficient conditions for a scalar type spectral
operator in a Banach space to be a generator of an infinite
differentiable or a Gevrey ultradifferentiable C0-semigroup
are found, the latter formulated exclusively in terms of the
operator's spectrum.