Problems in additive number theory, V: Affinely inequivalent MSTD sets
  An MSTD set is a finite set of integers with more sums than differences. It is proved that, for infinitely many positive integers $k$, there are infinitely many affinely inequivalent MSTD sets of cardinality $k$. There are several related open problems. 
Melvyn B. Nathanson
math.NT