Characterizations of inner product spaces by orthogonal vectors

Let X be a real normed space with unit closed ball B. We prove that X is an inner product space if and only if it is true that whenever x, y are points in ?B such that the line through x and y supports 22B then x?y in the sense of Birkhoff.

Bibliographic Details
Main Authors: Marco Baronti, Emanuele Casini
Format: Article
Language:English
Published: Hindawi Limited 2006-01-01
Series:Journal of Function Spaces and Applications
Online Access:http://dx.doi.org/10.1155/2006/521425