Hahn decomposition theorem
Let be a signed measure in the measurable space . There are two measurable sets and such that:
- 1.
and ;
- 2.
for each such that ;
- 3.
for each such that .
The pair is called a Hahn decomposition for .This decomposition is not unique, but any other such decomposition satisfies (where denotes the symmetric difference), so the two decompositions differ in a set of measure
0.