arXiv subjects
Publications and source records attributed to Javier Pello.
We introduce the notion of subprojective and superprojective operators and we use them to prove a variation of the three-space property for subprojective and superprojective spaces. As an application, we show that some spaces considered by Johnson and Lindenstrauss are both subprojective and superprojective.
We study the complemented subspaces of the $J$-sums of Banach spaces $J(\Phi)$ and $\hat J(\Phi)$ introduced by Bellenot. As an application, we show that, under some conditions, $J(\Phi)$ and $\hat J(\Phi)$ are subprojective, i.e., every closed infinite-dimensional subspace of either of them contains a complemented infinite-dimensional subspace.
We show that the perturbation class for the upper semi-Fredholm operators between two Banach spaces X and Y coincides with the strictly singular operators when X is subprojective and that the perturbation class for the lower semi-Fredholm operators coincides with the strictly cosingular operators when Y is superprojective. Similar results were previously obtained under stronger conditions for X and Y.
We show that the Banach space $C(K,X)$ is subprojective if $K$ is scattered and $X$ is subprojective.
We obtain some results for and further examples of subprojective and superprojective Banach spaces. We also give several conditions providing examples of non-reflexive superprojective spaces; one of these conditions is stable under $c_0$-sums and projective tensor products.