Let p:E→B Be a continuous subjective map. An open set U⊂B is considered evenly covered if p−1(U) is the disjoint union of some Vα, for each Vα⊂E, such that p∣Vα:Vα→U is a homeomorphsm. Each Vα is called a slice of E. If, for any b∈B, there exists a neighborhood U containing b that is evenly covere by p, then p is a covering map.