2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/61866Among other things, it is shown that there exist Banach spaces $Z$ and $W$ such that $Z^{**}$ and $W$ have bases, and for every $p\in[1,2)$ there is an operator $T:W\to Z$ that is not $p$-nuclear but $T^{**}$ is $p$-nuclear.15 pages, AMSTeX; misprint in Theorem 5, (v): now (W,X) is replaced by (W,Z)Functional Analysistext