Riemann–Hilbert problem
In mathematics, Riemann–Hilbert problems, named after Bernhard Riemann and David Hilbert, are a class of problems that arise in the study of differential equations in the complex plane. Specifically, a Riemann–Hilbert problem is a boundary value problem for a holomorphic function on the complement of an oriented contour in the complex plane, with prescribed jump discontinuities across the contour.