Two theorems on invariant submanifolds of product Riemannian manifold

In this paper we discuss the distributions of a Riemannian almost-product structure in product Riemannian manifold. We show that an invariant submanifold of a product Riemannian manifold has a Riemannian almost-product structure, and investigate properties of integral manifold of distributions of Riemannian almost-product structure, i.e., pseudo-umbilical submanifold and curvature-invariant submanifold.