374 research outputs found
On sectional and bisectional curvature of the H
Let M be an H-umbilical submanifold of an almost Hermitian
manifold M˜. Some relations expressing the difference of
bisectional and of sectional curvatures of M˜ and of M
are obtained. The geometric notion of related bases for a pair of
oriented planes permits to write the second members in a
completely geometrical form. When the planes are not orthogonal,
more simple formulas are obtained. The paper ends with a remark,
concerning the vector field JH, and some special cases
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