Published online by Cambridge University Press: 27 March 2018
We prove a robust version of Freiman's 3k – 4 theorem on the restricted sumset A+ΓB, which applies when the doubling constant is at most (3+$\sqrt{5}$)/2 in general and at most 3 in the special case when A = −B. As applications, we derive robust results with other types of assumptions on popular sums, and structure theorems for sets satisfying almost equalities in discrete and continuous versions of the Riesz–Sobolev inequality.
Supported by a Glasstone Research Fellowship.
Supported by a London Mathematics Society Undergraduate Research Bursary and the Mathematical Institute at University of Oxford.