A function f between two metric spaces M and N satisfies the Lipschitz condition if there exists a constant k for which d(f(x), f(y)) ≤ k d(x, y) for all points x, y in M, i.e. that the distance between the function values is bounded by a constant multiple of the distance between the values. Lipschitz functions are uniformly continuous and absolutely continuous. Compare contraction; see Rademacher’s theorem.