Isospectral flat orientable 2-orbifolds.
We construct new examples of compact Riemann surfaces which are non isometric but have the same spectrum of the Laplacian. Examples are given for genus and for all . In a second part we give examples of isospectral non isometric surfaces in which are realizable by paper models.
We give a full description of the semiclassical spectral theory of quantum toric integrable systems using microlocal analysis for Toeplitz operators. This allows us to settle affirmatively the isospectral problem for quantum toric integrable systems: the semiclassical joint spectrum of the system, given by a sequence of commuting Toeplitz operators on a sequence of Hilbert spaces, determines the classical integrable system given by the symplectic manifold and commuting Hamiltonians. This type of...
A flag manifold of a compact semisimple Lie group is defined as a quotient where is the centralizer of a one-parameter subgroup of . Then can be identified with the adjoint orbit of in the Lie algebra of . Two flag manifolds and are equivalent if there exists an automorphism such that (equivalent manifolds need not be -diffeomorphic since is not assumed to be inner). In this article, explicit formulas for decompositions of the isotropy representation for all flag manifolds...
The Ito equation is shown to be a geodesic flow of metric on the semidirect product space , where is the group of orientation preserving Sobolev diffeomorphisms of the circle. We also study a geodesic flow of a metric.