Completeness and Basis Properties of Complex Exponentials
Raymond M. Redheffer, R. Michael Young · Transactions of the American Mathematical Society · 1983
This paper is concerned with what might be termed the "fine structure" of the completeness and basis properties of complex exponentials. We give new criteria for two sequences to have the same excess in the sense of Paley and Wiener, a result that illuminates and supplements a well-known completeness criterion of Levinson, and new examples and counterexamples pertaining to Riesz bases.