 Covering space

In topology, a **covering space** is a topological space that "covers" another space in a specific, structured way. Formally, a covering space \( \tilde{X} \) of a space \( X \) is a space that satisfies the following conditions: 1. **Projection**: There is a continuous surjective map (called the covering map) \( p: \tilde{X} \to X \).

Basically it is a larger space such that there exists a surjection from the large space onto the smaller space, while still being compatible with the topology of the small space.

We can characterize the cover by how injective the function is. E.g. if two elements of the large space map to each element of the small space, then we have a double cover and so on.