By using an inequality relation between a scalar curvature and the length of the second fundamental form, it is proved that sectional curvatures of a submanifold must be nonnegative (or positive).
利用数量曲率与第二基本形式长度之间的一个不等式关系，证明了其子流形的截面曲率一定非负(或者为正)，并将此应用到紧致子流形上，得到一些结果。
Some sufficient conditions arc obtained, under which the Square length of the second fundamental form of the immerse hypcrsurfaces is a constant.
研究一类局部对称Riemann流形的紧致超曲面，得到了使浸入超曲面的第二基本形式模长的平方为常数的几个充分条件。
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