© 1981 by London Mathematical Society
On the Domain Invariance Theorem for Accretive Mappings
Osdorfer Landstrasse 311, 2000 Hamburg 55, West Germany
Let E be a Banach space. If D is a subset of E and R a mapping of D into E, then R is said to be accretive if and only if ||x y||
||(x y) + t(R(x) R(y))|| for all x, y
D and all t
0. Using only this defining property of accretive mappings, we give a straightforward and elementary proof of the important fact that T(U) is open, if U is an open subset of E and T : U
E is continuous, locally closed, locally one to-one and locally accretive.