Bourbaki

Corollary 1

Tag 0BZP, permanent. Cite it as [Bourbaki, Tag 0BZP].

General Topology, chapter VII, § 3. Infinite sums in the groups $\mathbf{R}^n$

If (aλ)λ∈L(a_\lambda)_{\lambda \in L} is a summable family of real numbers and if (xμ)μ∈M(x_\mu)_{\mu \in M} is a summable family of points of Rn\mathbf{R}^n, then the family (aλxμ)(λ,μ)∈L×M(a_\lambda x_\mu)_{(\lambda, \mu) \in L \times M} is summable and we have

∑(λ,μ)∈L×Maλxμ=(∑λ∈Laλ)(∑μ∈Mxμ). \sum_{(\lambda, \mu) \in L \times M} a_\lambda x_\mu = \left( \sum_{\lambda \in L} a_\lambda \right) \left( \sum_{\mu \in M} x_\mu \right).

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.