ABSTRACT
The Klein group is a commutative group of four transformations T1 through T4 such that composing two of the operations T2, T3, or T4 yields the third, and composing all three of them once again yields the identity operation T1. In this very general form, the Klein group can be found in all domains. The INRC group is a special case of the Klein group. Its characteristics are sharply delimited, and are not to be found outside of power set structures. The operations of the INRC group are thus operations of a higher power, or "operations on operations", and the origins of such higher-level operations pose a problem. This chapter focuses on the rotation problem, whose solution gives rise to the best-differentiated levels. It discusses the questions that call for comparisons between different situations, some of which involve a group structure, and some of which do not.
