We obtain an effective lower bound on the distance of the sum of co-adjoint orbits from the origin. Even when the distance is zero (thus the symplectic quotient is well defined) our result gives a nontrivial constraint on these co-adjoint orbits. In the particular case of unitary groups, we obtain the quadratic inequality for eigenvalues of Hermitian matrices satisfying A + B = C. This quadratic inequality can be interpreted as the Chern number inequality for semi-stable reflexive toric sheaves.

We give Chern-Weil definitions of the Maslov indices of bundle pairs over a Riemann surface with boundary, which consists of symplectic vector bundle on and a Lagrangian subbundle on\partial as well as its generalization for transversely intersecting Lagrangian boundary conditions. We discuss their properties and relations to the known topological definitions. As a main application, we extend Maslov index to the case with orbifold interior singularites, via curvature integral, and find also an analogous topological definition in these cases.