Researchers are recreating ancient odours for museumgoers as interest in the archaeology of smell grows
트럼프, 마두로때처럼 ‘親美 이란’ 노림수… 체제 전복도 언급
，详情可参考服务器推荐
Зеленскому стали чаще желать смерти02:42
08:16, 3 марта 2026Мир，更多细节参见体育直播
Фото: Benoit Tessier / Reuters。关于这个话题，体育直播提供了深入分析
The fundamental group of \(X\) at \(x_0\) is \[\pi_1(X, x_0) \;:=\; \bigl\{[\gamma] \mid \gamma \text{ is a loop based at } x_0\bigr\}\] equipped with the group operation of concatenation: \[[\gamma] \cdot [\delta] := [\gamma * \delta], \qquad (\gamma * \delta)(s) := \begin{cases} \gamma(2s) & s \in [0,\tfrac{1}{2}] \\ \delta(2s-1) & s \in [\tfrac{1}{2},1] \end{cases}\] The identity element is the class of the constant loop \([c_{x_0}]\), and the inverse of \([\gamma]\) is \([\bar\gamma]\) where \(\bar\gamma(s) := \gamma(1-s)\).