No CrossRef data available.
Published online by Cambridge University Press: 20 November 2018
The theory of gentle perturbations was introduced by Friedrichs [3] as a tool to study the perturbation theory of the absolutely continuous spectrum of a self-adjoint operator H 0 and developed in an abstract form by Rejto [7; 8]. Two examples of gentle structures are well knowTn. In the first of these, the gentle operators have Hölder continuous complex or operator-valued kernels, and in the second, the kernels are Fourier transforms of L 1 functions [4].
The gentle structure has traditionally been verified in the case when H 0 is in its spectral representation, that is, when H 0 is the simple differentiation operator. This is not the natural setting for the second example mentioned above where one should consider the simple differentiation operator in a suitable L 2-space and perturbations with L 1 kernels.