Periodic decomposition of measurable integer valued functions ✩

We study those functions that can be written as a sum of (almost everywhere) integer valued periodic measurable functions with given periods. We show that being (almost everywhere) integer valued measurable function and having a real valued periodic decomposition with the given periods is not enough. We characterize those periods for which this condition is enough. We also get that the class of bounded measurable (almost everywhere) integer valued functions does not have the so-called decomposition property. We characterize those periods a1, . . . , ak for which an almost everywhere integer valued bounded measurable function f has an almost everywhere integer valued bounded measurable (a1, . . . , ak)-periodic decomposition if and only if a1 ··· ak f = 0, where af (x) = f (x +a) − f (x). © 2007 Elsevier Inc. All rights reserved