Bourbaki

Proposition 10

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

Topologie algébrique, chapter I, § 2. Applications étales

Let E, B and Z be topological spaces, p:E→Bp: E\rightarrow B an étale mapping and f:Z→Bf: Z\rightarrow B a continuous mapping.

Let z∈Zz\in Z and x∈Ex\in E be points such that f(z)=p(x)f(z) =p(x). There exists a neighbourhood W of zz in Z and a continuous lifting gg of ff to E, defined on W, such that g(z)=xg(z) =x.

There exists an open neighbourhood V of p(x)p(x) in B and a continuous section ss of pp over V such that s(p(x))=xs(p(x)) =x (prop. 9). The set

W=f−1(V)W =\overset{-1}{f}(V) is an open neighbourhood of zz and the mapping g=s∘(f∣W)g=s\circ (f|W) is a continuous lifting of ff to E, defined on W and such that g(z)=xg(z) =x.

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.

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Machine translation of the English, by gpt-5.4, against glossary version 34. Not checked by a person.