Covering map implies local homeomorphism

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Statement

Suppose E and B are topological spaces and p:EB is a Covering map (?). Then, p is a Local homeomorphism (?).

Proof

Given: A covering map p:EB. A point eE.

To prove: There exists an open subset V of E containing e such that the restriction of p to V is a homeomorphism.

Proof:

Step no. Assertion Definitions used Previous steps used Explanation
1 Let b=p(e) -- --
2 There exists an open subset U of B such that bU, a discrete space F, and a homeomorphism φ:U×Fp1(U) such that pφ is projection on the first coordinate. covering map (1)
3 Let f be the second coordinate of φ1(e). Let V be φ(U×{f}). Then V contains e -- (2) By definition, φ1(e)U×{f}. Since φ is bijective, we get that eφ(U×{f}).
4 V is an open subset of p1(U) -- (2), (3) Since φ is a homeomorphism, it suffices to note that U×{f} is an open subset of U×F. This in turn follows from the fact that F being a discrete space, {f} is an open subset of F.
5 V is an open subset of E -- (2), (4) Since p is continuous and U is open in B, p1(U) is open in E. Step (4) says that V is open in p1(U). Combining, we get that V is open in E.
6 The restriction of p to V gives a homeomorphism from V to U. -- (2)-(5) We have that p=(pφ)φ1. Restricted to V, the map is the composite of a homeomorphism from V to U×{f} and a projection (homeomorphism) from U×{f} to U. Hence, the map overall is a homeomorphism.