Definition 3 A universal cover of a topological space \(X\) is a covering space \(\tilde{X}\) of \(X\) that is simply connected, meaning that it has no nontrivial loops. The universal cover is unique up to homeomorphism and serves as a “universal” object in the category of covering spaces of \(X\).
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“家乡太冷、偏远、小众，一年到头没啥人。”此前的他，自2016年大学毕业后，一直在外闯荡。