Rademacher's theorem
In mathematical analysis, Rademacher's theorem, named after Hans Rademacher, states the following: If is an open subset of Euclidean space| and is Lipschitz continuous, then is differentiable almost everywhere in ; that is, the points in at which is not differentiable form a set of Lebesgue measure zero.Generalizations
There is a version of Rademacher's theorem that holds for Lipschitz functions from a Euclidean space into an arbitrary metric space in terms of metric differentials instead of the usual derivative.
