The absolute continuity of functions defined on the -ring generated by a ring
The chain rule for differentiable measures
The converse of the Fatou theorem for smooth measures.
The hardy-littlewood maximal function and derivation of integrals.
The property of weak type (p,p) for the Hardy-Littlewood maximal operator and derivation of integrals
The Radon--Nikodym theorem for reflexive Banach spaces.
To the problem of a strong differentiability of integrals along different directions.