Torsion; second fundamental form; shape operator; integrable distributions
The second fundamental form of Riemannian geometry is generalised to the case of a manifold with a linear connection and an integrable distribution. This bilinear form is generally not symmetric and its skew part is the torsion. The form itself is closely related to the shape map of the connection. The codimension one case generalises the traditional shape operator of Riemannian geometry.
 Kobayashi, S., Nomizu, K.: Foundations of Differential Geometry
. 1, 1963, Wiley-Interscience, New York, MR 0152974
| Zbl 0119.37502
 Lee, J. M.: Riemannian manifolds: an introduction to curvature
. 1997, Springer-Verlag, New York, MR 1468735
| Zbl 0905.53001