First we introduce the notion of parallel Ricci tensor ${\nabla }\mathrm {Ric}=0$ for real hypersurfaces in the complex quadric Qm = SOm+2/SOmSO2 and show that the unit normal vector field N is singular. Next we give a new classification of real hypersurfaces in the complex quadric Qm = SOm+2/SOmSO2 with parallel Ricci tensor.

中文翻译：

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复二次曲面中实超曲面的平行 Ricci 张量新分类

首先我们介绍并行里奇张量的概念${\nabla }\mathrm {Ric}=0$对于复二次曲面中的真实超曲面问米=所以米+2/所以米所以2并证明单位法向量场ñ是单数。接下来我们给出复二次曲面中真实超曲面的新分类问米=所以米+2/所以米所以2具有平行 Ricci 张量。