Homework for Math 362A
Spring, 2008


Problem Set

Chapter

Problems

27 ∗43 In Note L.26 we pointed out that a linear combination f of characteristic functions is measurable if and only if each of the characteristic functions is for a measurable set. Prove this statement. (The term linear combination is being used here just as it is used in linear algebra (MATH 255/256 or MATH 352) or differential equations (MATH 231/333). For the definition of this term, given in the context of vectors xi rather than functions, see Rudin, p. 204.)
11 3 -- In proving this result, you may make the additional assumption that for each x in X, (fn(x)) is a bounded sequence. (That is, there is a number Mx > 0 for which |fn (x)| ≤ Mx. As x changes, we must assume Mx does to.)
Challenge: Prove the result without this additional assumption (i.e., the result as it is stated in Rudin.)

Notation

n manditory problem
∗n manditory problem, not from text
(n) helper problem
[n] ungraded problem
[∗n] ungraded problem, not from text
{n} optional problem