${\ell }^1$-Bounded Sets

Christopher Heil, Pu-Ting Yu

A subset $M$ of a separable Hilbert space $H$ is ${\ell }^1$-bounded if there exists a Riesz basis $\mathcal{F}=\{e_n{\}}_{n\in \mathbb{N}}$ for $H$ such that $\sup_{x \in M} \sum_{n…