Measure, Integration & Real Analysis · Problem 3A.9
Integration — Sheldon Axler
Mathematics — Measure Theory · integral-defines-measure
Problem
Suppose μ is a measure on a measurable space (X,S) and f:X→[0,∞] is an S-measurable function. Define ν:S→[0,∞] by
ν(A)=∫χAfdμ
for A∈S. Prove that ν is a measure on (X,S).