COUNTING SUMSETS AND DIFFERENCES IN ABELIAN GROUP
Subset A of a group G is called (k, l)-sumset, if A = kB - lB for some B  G, where kB - lB = {x 1 + ∙∙∙ + x k - x k+1- ∙∙∙ - x k+l | x 1,...,x k+1  ∈ B}. Upper and lower bounds for the numbers of (1,1)-sumsets and (2,0)-sumsets in abelian groups are provided.