Abstract

Derndinger [2] and Krupa [5] defined the F-product of a semigroup and presented some applications . Wolff investigated some kind of nonstandard analogon and applied it to spectral theory of group representations. The question arises in which way these constructions are related. In this paper we show that the classical and the nonstandard F-product are isomorphic . We also prove a little “classical” corollary