Homework Statement
The question is from Stein, "Analysis 2", Chapter 1, Problem 5:
Suppose E is measurable with m(E) < ∞, and E = E1 ∪ E2, E1 ∩ E2 = ∅.
Prove:
a) If m(E) = m∗(E1) + m∗(E2), then E1 and E2 are measurable.
b) In particular, if E ⊂ Q, where Q is a finite cube, then...