In mathematics, the covariant derivative is a way of specifying a derivative along tangent vectors of a manifold. Alternatively, the covariant derivative is a way of introducing and working with a con
Ковариантная производная c
In mathematics, the differential geometry of surfaces deals with the differential geometry of smooth surfaces with various additional structures, most often, a Riemannian metric.
Carl Friedrich Gauss in 1828
Bernhard Riemann (1826-1866)
A single-sheeted quadric hyperboloid which is a ruled surface in two different ways.
Eugenio Beltrami (1835-1899)