ON THE GENERICITY OF NONVANISHING INSTABILITY INTERVALS IN PERIODIC DIRAC SYSTEMS

Using Floquet-Lyapunov theory, it is shown that for Baire-almost every periodic potential the Dirac system has all its instability intervals open. Consequently, one-dimensional Dirac operators with periodic pot entials generically possess infinitely many spectral gaps. These resul ts also hold true if only even potentials are admitted.