Contractive projections in Paley-Wiener spaces

Abstract

Let S 1 S_1 and S 2 S_2 be disjoint finite unions of parallelepipeds. We describe necessary and sufficient conditions on the sets S 1 , S 2 S_1,S_2 and exponents p p such that the canonical projection P P from P W S 1 ∪ S 2 p PW_{S_1\cup S_2}^p to P W S 1 p PW_{S_1}^p is a contraction.