On Bicheng[Yang]-Debnath's generalizations of Hardy's integral inequality.
Let and be a positive integer. Let be a locally bounded map such that for each , the derivatives , , exist and are continuous. In order to conclude that any such map is necessarily of class it is necessary and sufficient that be not contained in the zero-set of a nonzero homogenous polynomial which is linear in and homogeneous of degree in . This generalizes a result of J. Boman for the case . The statement and the proof of a theorem of Boman for the case is also extended...
We study possible Borel classes of sets of Fréchet subdifferentiability of continuous functions on reflexive spaces.