Automorphism Groups of Classical Mechanical Systems.
In this paper we prove that the maximum dimension of the Lie group of automorphisms of the Riemann–Cartan 4-dimensional manifold does not exceed 8, and if the Cartan connection is skew-symmetric or semisymmetric, the maximum dimension is equal to 7. In addition, in the case of the Riemann–Cartan -dimensional manifolds with semisymmetric connection the maximum dimension of the Lie group of automorphisms is equal to for any .
In the present paper we answer two questions raised by Barbilian in 1960. First, we study how far can the hypothesis of Barbilian's metrization procedure can be relaxed. Then, we prove that Barbilian's metrization procedure in the plane generates either Riemannian metrics or Lagrance generalized metrics not reducible to Finslerian or Langrangian metrics.
On montre l’équivalence entre l’hyperbolicité au sens de Gromov de la géométrie de Hilbert d’un domaine convexe du plan et la non nullité du bas du spectre de ce domaine.