Warped Product CR-Submanifolds of Lorentzian -Kenmotsu Manifolds
Warped product semi-invariant submanifolds in almost paracontact Riemannian manifolds.
Warped product submanifolds of cosymplectic manifolds.
Willmore submanifolds in the unit sphere.
In this paper we generalize the self-adjoint differential operator (used by Cheng-Yau) on hypersurfaces of a constant curvature manifold to general submanifolds. The generalized operator is no longer self-adjoint. However we present its adjoint operator. By using this operator we get the pinching theorem on Willmore submanifolds which is analogous to the pinching theorem on minimal submanifold of a sphere given by Simon and Chern-Do Carmo-Kobayashi.