Spectra and geodesic flows on nilmanifolds: Reductions of Hamiltonian systems and differential operators
Spectra and geodesic flows on nilmanifolds: Reductions of Hamiltonian systems and differential operators
TWO compact Riemannian manifolds are said to be isospectral if their asso- ciated Laplace-Beltrami operators have the same spectra.In 1964 J. Milnor [15] first gave an example of a pair of isospectral 16-dimensional flat tori which are not isometric to each other.Later, other examples of pairs of iso- spectral but …