Extensions of (weakly) null-additive, monotone set functions from rings of subsets to generated algebras

This paper shows that the greatest and least monotone extensions of a null-additive (resp. weakly null-additive), monotone set function from a ring of subsets to the algebra generated by the ring are null-additive (resp. weakly null-additive). In addition, the paper characterizes all the (weakly) null-additive, monotone extensions.