Bourbaki

Exercise 24, § 4

General Topology, II, p. 41

Let XX be a locally compact and locally connected space, YY a separated space, f:X→Yf : X \to Y a continuous mapping. Let xx be a point of XX such that the subspace f−1(f(x))f^{-1}(f(x)) of XX is totally disconnected. Show that when UU runs through a fundamental system of neighbourhoods of f(x)f(x) in YY, the connected components of xx in the sets f−1(U)f^{-1}(U) form a fundamental system of neighbourhoods of xx. (Reason by contradiction, using Exercise 14 of II, p. 38).

Solution

No solution has been written yet.

Machine translation of the English, by gpt-5-mini. Not checked by a person. That model is a cut down version of the one the rest of this language was written by.