Uniform partitions of frames of exponentials into Riesz sequences

Abstract

The Feichtinger Conjecture, if true, would have as a corollary that for each set $E\subset \T$ and $\Lambda \subset \Z$, there is a partition $\Lambda_1,...,\Lambda_N$ of $\Z$ such that for each $1\le i \le N$, $\{\exp(2\pi i x\lambda): \lambda \in \Lambda_i\}$ is a Riesz sequence. In this paper, sufficient conditions on sets $E\subset \T$ and $\Lambda\subset \R$ are given so that $\{\exp(2\pi i x\lambda) 1_E: \lambda \in \Lambda\}$ can be uniformly partitioned into Riesz sequences.