Approximation spaces, greedy classes and Lorentz spaces
arXiv:2411.13678
Abstract
We characterize the approximation spaces of a broad class of bases - which includes almost greedy bases - in terms of weighted Lorentz spaces. For those bases, we also find necessary and sufficient conditions under which the approximation spaces and greedy classes are the same.
V3: We corrected and improved Lemma 3.7, and adjusted the related results accordingly. V4: We added the Chebyshev-Greedy classes, and fixed some typos