Disjoint strict singularity of inclusions between rearrangement invariant spaces
It is studied when inclusions between rearrangement invariant function spaces on the interval [0,∞) are disjointly strictly singular operators. In particular suitable criteria, in terms of the fundamental function, for the inclusions and to be disjointly strictly singular are shown. Applications to the classes of Lorentz and Marcinkiewicz spaces are given.