Schild's ladder

For the book, see Schild's Ladder.
Two rungs of Schild's ladder. The segments A1X1 and A2X2 are an approximation to first order of the parallel transport of A0X0 along the curve.

In the theory of general relativity, and differential geometry more generally, Schild's ladder is a first-order method for approximating parallel transport of a vector along a curve using only affinely parametrized geodesics. The method is named for Alfred Schild, who introduced the method during lectures at Princeton University.