Bourbaki

Corollary 2

Tag 0896, permanent. Cite it as [Bourbaki, Tag 0896].

Functions of a Real Variable, chapter II, § 3. DERIVATIVES AND INTEGRALS OF FUNCTIONS DEPENDING ON A PARAMETER

Let AA be a subset of a topological space FF, and ff a map of I×AI \times A into a complete normed space EE over R\mathbf{R}, such that, for every α∈A\alpha \in A, the function x↦f(x,α)x \mapsto f(x, \alpha) is regulated on II. If, on the one hand, the functions x↦f(x,α)x \mapsto f(x, \alpha) converge uniformly on every compact interval contained in II to a function x↦f(x)x \mapsto f(x) as α\alpha tends to α0∈A‾\alpha_0 \in \overline{A} while remaining in AA; if, on the other hand, the integral ∫If(x,α) dx\int_I f(x, \alpha)\,dx is uniformly convergent on AA, then the integral ∫If(x) dx\int_I f(x)\,dx is convergent, and one has

lim⁡α→α0, α∈A∫If(x,α) dx=∫If(x) dx. \lim_{\alpha \to \alpha_0,\ \alpha \in A} \int_I f(x, \alpha)\,dx = \int_I f(x)\,dx.
(10)

In particular:

Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.

Cited by

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Cites

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Transcribed from the printed volume. Not translated.