It is proven that if X is a real strictly convex 2-dimensional space, then there exists delta > 0 such that if K and S are locally compact Hausdorff spaces and T is an isomorphism from C-0(K, X) onto C-0(S, X) satisfying ||T|| ||T-1|| <= lambda(X) + delta,then K and S are homeomorphic. Here lambda(X) is the Schaffer constant of X given by lambda(X) = inf{max{||x-y||, ||x + y||} : ||x|| =1 and ||y|| = 1}.Even for the classical cases X = P-p(2), 1 < p < infinity, this result is the form of Banach-Stone theorem to C0(K, X) spaces with the largest known distortion ||T|| ||T-1||. In particular, it shows that the Banach-Stone constant of g, is strictly greater than 2(1-1/p) if 1 < p <= 2 and strictly greater than 2(1/p) if 2 <= p < infinity. Until then this theorem had only been proved for p = 2.
机构:
Univ Sao Paulo, Dept Math, IME, Rua Matao, Sao Paulo, Brazil
Univ Sao Paulo, Dept Math, IME, Rua Matao 1010, Sao Paulo, BrazilUniv Sao Paulo, Dept Math, IME, Rua Matao, Sao Paulo, Brazil