ABSTRACT
Chapters 2 and 3 have to do with morphisms linked to rotations of varying degree and complexity. In chapter 2, the rotations involve cyclic successions of several elements; in chapter 3, they involve rotations of a cube. It makes sense, therefore, to begin with the simplest situation where the positions of a single object, for example, the head and feet of a doll, vary according to the rotations and circumductions to which they are subjected and where morphisms consist only in linking starting to ending points by means of transformations.
