Interpolation of Operators on Decreasing Functions.
Weighted Hardy inequalities and Hardy transforms of weights
Many problems in analysis are described as weighted norm inequalities that have given rise to different classes of weights, such as -weights of Muckenhoupt and -weights of Ariño and Muckenhoupt. Our purpose is to show that different classes of weights are related by means of composition with classical transforms. A typical example is the family of weights w for which the Hardy transform is -bounded. A -weight is precisely one for which its Hardy transform is in , and also a weight whose indefinite...
Endpoint estimates from restricted rearrangement inequalities.
Extrapolation theory for the real interpolation method.
We develop an abstract extrapolation theory for the real interpolation method that covers and improves the most recent versions of the celebrated theorems of Yano and Zygmund. As a consequence of our method, we give new endpoint estimates of the embedding Sobolev theorem for an arbitrary domain Omega.
Interpolation of quasicontinuous functions
If C is a capacity on a measurable space, we prove that the restriction of the K-functional to quasicontinuous functions f ∈ QC is equivalent to . We apply this result to identify the interpolation space .
Characterization of rearrangement invariant spaces with fixed points for the Hardy-Littlewood maximal operator.
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