Bourbaki

Exercise 16, § 2

Integration, VI, p. 66

Consider the mappings umu_m of T=[0,1]T = [0, 1] into a separable Hilbert space, defined in §1, Exer. 1, and set fk=u1+⋯+ukf_k = u_1 + \cdots + u_k; show that the vectorial measures fk⋅μf_k \cdot \mu converge uniformly on every bounded subset of C(T)C(T) to a vectorial measure mm with values in FF. Moreover, mm may be extended by continuity to the space L2(μ)L^2(\mu) and, for every function f∈L2f \in L^2, one has ∫fdm∈F\int f dm \in F and ∣∫fdm∣≤N2(f)|\int f dm| \leq N_2(f) in FF; in particular, mm is scalarly of base μ\mu and absolutely continuous with respect to μ\mu for the strong topology (Exer. 12 c)). However, mm is not of base ν\nu for any positive measure ν\nu on TT, and a fortiori (No. 5, Cor. 4 of Th. 1) is not majorizable. (Reduce to the case that ν\nu has base μ\mu, using Th. 3 of Ch. V, §5, No. 7.)

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