Authors: Arnautov Vladimir, Ursul M. I.
Abstract
The concept of strong isomorphism of groups is introduced that gives conditions when the number of different $Q$-middle groups of $P$-symmetry and the number of different junior groups of $P_0$-symmetry coincide. With using the strong isomorphism the concept of isomorphism of $P$-symmetries is made more precise.
Institutul de Matematica Academia de Stiinte a Moldovei
str. Academiei 5, MD-2028 Chisinau, Moldova