García-Pacheco, F.J.Seoane Sepúlveda, Juan Benigno2023-06-202023-06-2020070035-759610.1216/rmjm/1187453103https://hdl.handle.net/20.500.14352/50491We give a new and direct proof of the fact that, in any infinite dimensional Banach space, the unit sphere minus any one point is homeomorphic to a closed hyperplane. The proof involves L-structures and geometric concepts as, for instance, rotund, smooth and exposed points.engjournal articlehttp://projecteuclid.org/euclid.rmjm/1187453103open access517.98Unit sphereClosed hyperplaneStereographic projectionL2-summand vectorAnálisis funcional y teoría de operadores