A survey of nearisometries
Abstract
Description
Let E and F be Banach spaces, let A be a subset of E, and let s \ge 0. A map f: A -> F is an s-nearisometry if |x-y|-s \le |fx-fy| \le |x-y|+s for all x,y in A. The article gives a survey on the stability problem: How well can an s-nearisometry be approximated by a true isometry? The first result on this problem was given by Hyers and Ulam in 1945 for surjective nearisometries between Hilbert spaces.
The present article contains an addendum to the published paper, giving recent results on nearsurjective maps of Banach spaces.
15 pages. Contains an addendum to the published paper
15 pages. Contains an addendum to the published paper