In this paper it is demonstrated
that if μ is an additive function from a field F into the nonnegative reals, then μ can
be separated into two mutually singular parts, μ1 and μ2, where μ1 is representable
in the sense that its Lebesgue decomposition projection operator has a refinement
integral representation and μ2 is such that for each E ∈ F the contraction of μ2 to E
is representable iff μ2(E) = 0. If μ2 is maximal, then the decomposition is
unique.