Complemented Hilbertian subspaces in rearrangement invariant function spaces (Q1892737)

The author provides the details and further investigations to [the author; Séminaire d'Initiation à l'analyse, 32ème année, Expo. No. 15 (1993; review above)], concerning the rearrangement invariant function spaces \(X\), their Hilbertian subspaces and Hilbert valued extensions \(X(\ell_2)\). For a reference to rearrangement invariant function spaces, see \textit{J. Lindenstrauss} and \textit{L. Tzafriri} [``Classical Banach spaces. II: Function spaces'' (1979; Zbl 0403.46022)].