A Decomposition Theorem for Topological Semi-small Maps
A continuous surjection $f: X \rightarrow Y$ is an almost covering map if there exists a nowhere dense closed set $R \subset Y$ with a finite decomposition $R = \bigsqcup_{\beta} T_{\beta}$ such that the restriction $f\vert_{f^{-1}(Y \setminus R)}$ is a covering map and, for each $\beta$, the restriction $f\vert_{f^{-1...