Marcinkiewicz multipliers and multi-parameter structure on Heisenberg (-type) groups, II.
We investigate several aspects of almost 1-unconditionality. We characterize the metric unconditional approximation property (umap) in terms of “block unconditionality”. Then we focus on translation invariant subspaces and of functions on the circle and express block unconditionality as arithmetical conditions on E. Our work shows that the spaces , p an even integer, have a singular behaviour from the almost isometric point of view: property (umap) does not interpolate between and . These...
A multiresolution analysis is defined in a class of locally compact abelian groups . It is shown that the spaces of integrable functions and the complex Radon measures admit a simple characterization in terms of this multiresolution analysis.