Bourbaki

Corollary 2

Tag 0890, permanent. Cite it as [Bourbaki, Tag 0890].

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 from I×AI \times A into a complete normed space EE over R\mathbf{R}, such that, for each α∈A\alpha \in A, the function x↦f(x,α)x \mapsto f(x, \alpha) is regulated on II. If the functions x↦f(x,α)x \mapsto f(x, \alpha) converge uniformly on II to a (regulated) function x↦g(x)x \mapsto g(x), as α\alpha tends to a point α0∈A‾\alpha_0 \in \overline{A} while remaining in AA, then one has

lim⁡α→α0, α∈A∫abf(x,α) dx=∫abg(x) dx. \lim_{\alpha \to \alpha_0,\ \alpha \in A} \int_a^b f(x, \alpha)\, dx = \int_a^b g(x)\, dx.

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.