Example

Tag 01LQ, permanent. Cite it as [Bourbaki, Tag 01LQ].

Topologie algébrique, chapter I, § 1. Produits fibrés et carrés cartésiens

Let $(X, p)$ be a B-space and A a subspace of B. The square

$\overset{-1}{p}(A)^j$ X

p_{_A}p \tag{5}

A $^i$ B

(where $i$ and $j$ are the canonical injections) is Cartesian.

In particular, if A and $A'$ are subspaces of the topological space B, the square

A\cap A'A'

(6)

A B

(where the arrows are the canonical injections) is Cartesian.

Bourbaki sets the proof directly after the statement, and the corpus does not separate them, so what is above is the statement and its proof together.

Cited by

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Cites

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