The Riemannian curvature of a differentiable Riemannian manifold $M$ at a point $p$ in the direction of a two-dimensional plane $\alpha$ (in the direction of the bivector that defines $\alpha$ at $p\in M$).
|[a1]||W. Klingenberg, "Riemannian geometry" , de Gruyter (1982) (Translated from German)|
Sectional curvature. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Sectional_curvature&oldid=31655