  This is a survey article dedicated to the study of topological quantities in
theory of normal metals discovered in the works of the authors during the last
years. Our results are based on the theory of dynamical systems on Fermi
surfaces. The physical foundations of this theory (the so-called "Geometric
Strong Magnetic Field Limit") were found by the school of I.M.Lifshitz many
years ago. Here the new aspects in the topology of quasiperiodic functions are
developed.
