Rohrbach's conjecture asserts that, for each positive integer 
, every finite group 
has a subset 
with 
and 
, where 
depends only on 
(Rohrbach 1937). Here 
consists of ordered products of exactly 
elements of 
, with repetition allowed. The
exponent 
is optimal because 
.
Yang (2026) proved the conjecture for all finite groups, without an Abelian hypothesis. More generally, there is an absolute constant 
such that, for every 
, 
, and nonnegative real 
, ..., 
with sum 1, there are subsets 
satisfying 
, 
, and 
for 
. Consequently 
is permitted. The constant is not asserted to be
sharp.
