Lipschitz inverse mapping theorem
Let be a Banach space and let be abounded linear isomorphism withbounded inverse (i.e. a topological linear automorphism
);let be the ball with center 0and radius (we allow ). Then for any Lipschitz mapsuch that and , there are open sets and and a map such that and .In other words, there is a local inverse of near zero. Furthermore, the inverse is Lipschitz with and
Remark. The inclusion above implies that is invertible if .
Remark. denotes the smallest Lipschitz constant of .