%0 Journal Article %A Azagra Rueda, Daniel %T Diffeomorphisms between spheres and hyperplanes in infinite-dimensional Banach spaces %D 1997 %@ 0039-3223 %U https://hdl.handle.net/20.500.14352/57010 %X We prove that for every infinite-dimensional Banach space X with a Frechet differentiable norm, the sphere S-X is diffeomorphic to each closed hyperplane in X. We also prove that every infinite-dimensional Banach space Y having a (not necessarily equivalent) C-p norm (with p is an element of N boolean OR {infinity}) is C-p diffeomorphic to Y \ {0}. %~