Title: Construction of dynamical semigroups by a functional regularisation à la Kato,
Abstract: A functional version of the Kato one-parametric regularisation for the
construction of a dynamical semigroup generator of a relative bound one
perturbation is introduced. It does not require that the minus generator of the
unperturbed semigroup is a positivity preserving operator. The regularisation
is illustrated by an example of a boson-number cut-off regularisation.