Lower bound for the size of a Bohr set
= Lower bound for the size of a Bohr set
A <Bohr set> of rank $d$ and width $\rho$ satisfies
$$
|B(\Gamma,\rho)|\geq\left(\frac{\rho}{8}\right)^d|G|.
$$
The proof partitions each circle coordinate into arcs and applies translation averaging and the pigeonhole principle.