Small product sets in compact groups

Artikel i vetenskaplig tidskrift, 2017

We show that a subcritical pair (A, B) of su ffi ciently "spread-out" Borel sets in a compact and second countable group K with an abelian identity component must reduce to a Sturmian pair in either T or T proportional to {-1, 1} . This extends a classical result of Kneser.