Connections with the tensor property associated with a quaternionic projective transformation. (Connexions ayant la propriété tensorielle associées à une transformation projectif quaternionique.)
I vari metodi di definire connessioni adattate ad un Riferimento fisico vengono qui ricondotti ad un unico formalismo. Viene inoltre introdotta la nozione generale di campo gravitazionale affine adattato (sia al Riferimento che alla connessione).
Nous illustrons une classification des espace-temps (2+1) globalement hyperboliques a courboure constant, en terms de certaines structures projectives complexes portées par les surfaces de niveau de leur temps cosmologique canonique. Ceci derive d’une theorie des rotations de Wick canoniques, developpée en collaboration avec Riccardo Benedetti [6], qui sera egalement brievement illustrée.
In this paper we obtain an interesting relation between the covariant derivatives of the Jacobi operator valid for all geodesic on the flag manifold . As a consequence, an explicit expression of the Jacobi operator independent of the geodesic can be obtained on such a manifold. Moreover, we show the way to calculate the Jacobi vector fields on this manifold by a new formula valid on every g.o. space.