摘要
Ⅰ. INTRODUCTIONLet M be a Riemannian manifold with the Levi-Civita connection ▽. A symmetric 2-tensor field A on M is called a Codazzi tensor if the covariant derivative ▽A of A is a symmetric 3-tensor field. The notion, obviously, originates from the second
基金
Project supported by the National Natural Science Foundation of China and by the Science Foundation of Zhejiang Province.
