Diagonal extendible multilinear operators between \(\ell_p\)-spaces (Q740706)

It is well known that there is no Hahn-Banach (extension) theorem for linear operators (instead of linear functionals) and also there is not a general multilinear version of the Hahn-Banach theorem (even for multilinear forms). In this interesting paper, the authors investigate the extendibility of diagonal multilinear operators from \(l_{p}\) to \(l_{q}\) spaces. For instance, among other results, the authors determine the values of \(p\) and \(q\) for which every diagonal \(n\)-linear operator is extendible, and those for which the only extendible ones are integral.