
Artículos Aizpuru: mber that a closed subspace M of a real Banach space X is said to be an L2- summand subspace if there exists another closed subspace N of X verifying X = (M ® N)2 (that is, ¡m + n||2 = ||m||2 + ||n||2 for every m e M and every n g N.) The linear projection t?m of X onto M that fixes the elements of M and maps the elements of N to {0} is called the L2-summand projection of X onto M. For a wider perspective about L2-summand subspaces,...