On a question of Cochrane and Pinner concerning multiplicative subgroups
Answering a question of T. Cochrane and C. Pinner, we prove that for any ε>0, sufficiently large prime number p and an arbitrary multiplicative subgroup R of the field Z/pZ, p^ε < |R| < p^{2/3-ε} the following holds |R + R|, |R - R| > |R|^{3/2+δ}, where δ>0 depends on ε only.
math.NT↗