Where \ nabla _ \ mu denotes covariant differentiation with respect to the metric g _ { \ mu \ nu }, while V _ G, V _ \ mu, and V _ \ omega are the self-interaction potentials associated with the scalar fields.
12.
In a famous 1869 paper on the equivalence problem for differential forms in " n " variables, published in Crelle's Journal, he introduced the fundamental technique later called covariant differentiation and used it to define the Riemann Christoffel tensor ( the most common method used to express the curvature of Riemannian manifolds ).
