Definition 4 (Definition: Fundamental Group) Let \(X\) be a topological space and \(x_0 \in X\) a basepoint. A loop based at \(x_0\) is a continuous map \(\gamma: [0,1] \to X\) with \(\gamma(0) = \gamma(1) = x_0\). Two loops \(\gamma, \delta\) are homotopic relative to \(x_0\) (written \(\gamma \simeq \delta\)) if there exists a continuous map \(H: [0,1] \times [0,1] \to X\) such that \[H(s,0) = \gamma(s), \quad H(s,1) = \delta(s), \quad H(0,t) = H(1,t) = x_0\] for all \(s,t \in [0,1]\). This is an equivalence relation; denote the equivalence class of \(\gamma\) by \([\gamma]\).
南方周末：所以在你看来，韩国是一种特殊的殖民地吗？
Donald Trump said Monday he will attend the White House correspondents’ association dinner for the first time as president.。业内人士推荐体育直播作为进阶阅读
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，更多细节参见体育直播
同样的事情，也在其他公司身上发生着，而且有些细节更为戏剧性。
Израиль нанес удар по Ирану утром 28 февраля. В Тегеране прогремело как минимум три взрыва. Удары были нанесены по резиденции иранского лидера Масуда Пезешкиана, штабу разведки Корпуса стражей исламской революции (КСИР) и аэропорту в Тегеране. В атаке приняли участие также Соединенные Штаты.。服务器推荐是该领域的重要参考