A continuous surjection p : E → B such that every b ∈ B has a neighbourhood U with p^{−1}(U) a disjoint union of copies of U each mapped homeomorphically. Universal cover classifies π_1(B)-principal bundles.
A continuous surjection p : E → B such that every b ∈ B has a neighbourhood U with p^{−1}(U) a disjoint union of copies of U each mapped homeomorphically. Universal cover classifies π_1(B)-principal bundles.