In this paper we study the convergence of Riemannian submanifolds. In particular, we prove that any sequence of closed submanifolds with bounded normal curvature and volume in a closed Riemannian manifold subconverge to a closed submanifold in the C1 ,Q topology. We also obtain some applications to irreducible homogeneous manifolds and pseudo-holomorphic curves in symplectic manifolds.

We introduce a series of invariants on Kähler manifolds and prove a series of general inequalities involving these invariants for Kähler submanifolds in complex space forms. We also determine Kähler submanifolds in complex space forms which satisfy the equality cases of these inequalities. MSC 2000: 53C40, 53C42 (primary); 53C55 (secondary)

In this note we prove that a positive multiple of each even-dimensional integral homology class of a compact symplectic manifold (M2n, ω) can be represented as the difference of the fundamental classes of two symplectic submanifolds in (M2n, ω). We also prove the realizability of some integral homology classes by symplectic submanifolds in (M2n, ω).

Generalized complex geometry encompasses complex and symplectic geometry as its extremal special cases. We explore the basic properties of this geometry, including its enhanced symmetry group, elliptic deformation theory, relation to Poisson geometry, and local structure theory. We also define and study generalized complex branes, which interpolate between flat bundles on Lagrangian submanifold...

In this paper, we study warped product CR-submanifolds of LP-cosymplectic manifolds. We have shown that the warped product of the type M = NT × fN⊥ does not exist, where NT and N⊥ are invariant and anti-invariant submanifolds of an LP-cosymplectic manifold M̄ , respectively. Also, we have obtained a characterization result for a CR-submanifold to be locally a CRwarped product.

We characterize general symplectic manifolds and their structure groups through a family of isotropic or symplectic submanifolds and their diffeomorphic invariance. In this way we obtain a complete geometric characterization of symplectic diffeomorphisms and a reinterpretation of symplectomorphisms as diffeomorphisms acting purely on isotropic or symplectic submanifolds. DOI: 10.1134/S008154380...

Oprea proves that Ric(X) ≤ n−1 4 (c + n||H||) improving the Chen-Ricci inequality for Lagrangian submanifolds in complex space forms by using an optimization technique. In this article, we give an algebraic proof of the inequality and completely classify Lagrangian submanifolds in complex space forms satisfying the equality, which is not discussed in Oprea’s paper.

By using two new algebraic lemmas we obtain Chen’s inequalities for submanifolds of a Riemannian manifold of nearly quasi-constant curvature endowed with a semi-symmetric non-metric connection. Moreover, we correct a result of C. Özgür and A. Mihai’s paper (Chen inequalities for submanifolds of real space forms with a semi-symmetric non-metric connection, Canad. Math. Bull. 55 (2012), 611–622).

In this paper, we would like to study space-like submanifolds in a de Sitter spaces S p (1). We define and discuss three Schrödinger operators LH , LR, LR/H and obtain some spectral characterizations of totally umbilical space-like submanifolds in terms of the first eigenvalue of the Schrödinger operators LH , LR and LR/H respectively.

CR singularities of real 4-submanifolds in complex 3-space are classified by using local holomorphic coordinate changes to transform the quadratic coefficients of the real analytic defining equation into a normal form. The quadratic coefficients determine an intersection index, which appears in global enumerative formulas for CR singularities of compact submanifolds.