On 2-Harmonic Space-Like Submanifolds of a Locally Symmtric Pseudo-Rimannian Manifold
关于局部对称伪黎曼流形中的2-调和类空子流形

Let Npn+p be a locally symmetric pseudo-Riemanian manifold, whose sectional curvatrue KN satisties $0<\delta\leqslant KN\leqslant1$. Let Mn be a 2-harmonic space-like submanifold in Npn+p. In this paper, we obtain a pinching theorem for the square of the length of the second fundamental form and an integral formula.