CONTENTS 0. Introduction.............................................................................5 1. Submultiplicative functions and indices...................................7 2. Indices of measurable functions...........................................12 3. Indices of Orlicz spaces........................................................19 4. Indices of rearrangement invariant spaces...........................25 5. Interpolation theorems for weak type operators....................29 6. Some additional remarks and open problems.......................39 A. Indices of Lorentz-Orlicz spaces..........................................39 B. Marcinkiewicz interpolation theorem in Orlicz spaces...........41 C. Indices and strong interpolation..........................................43 D. Indices and interpolation of compact operators...................45 References...............................................................................47
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