A covering space of a topological space 
is a pair 
, where 
is a topological space
and 
is a surjective continuous
map such that every 
has an open neighborhood 
whose inverse
image is a disjoint union of open
sets, each mapped homeomorphically onto 
by 
.
Covering Space
See also
Covering Map, Deck Transformation, Étale Morphism, Fundamental Group, Universal CoverExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Covering Space." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/CoveringSpace.html