-spaces and -spaces
Pointwise and global sums and negatives of binary relations.
Projections, extendability of operators and the Gâteaux derivative of the norm.
Pseudocomplémentation dans les espaces de Banach
This paper introduces the following definition: a closed subspace Z of a Banach space E is pseudocomplemented in E if for every linear continuous operator u from Z to Z there is a linear continuous extension ū of u from E to E. For instance, every subspace complemented in E is pseudocomplemented in E. First, the pseudocomplemented hilbertian subspaces of are characterized and, in with p in [1, + ∞[, classes of closed subspaces in which the notions of complementation and pseudocomplementation...