Some properties of regular and rational sets
Volume 182 / 2018
Acta Arithmetica 182 (2018), 279-284 MSC: 11B75, 37A45. DOI: 10.4064/aa170429-14-10 Published online: 12 January 2018
We study properties of rational and regular sets of integers. The main result is that every rational set can be split into two regular ones. It follows that the union of two regular sets need not be regular. This answers a question of Bergelson and Ruzsa.