Nature, Published online: 25 February 2026; doi:10.1038/d41586-026-00293-6
if next1 == 91:
，详情可参考体育直播
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 \(\bar\gamma(s) := \gamma(1-s)\).
agent:main:discord:channel:1468834856187203680 # Discord 某个频道的会话
Крупнейшая нефтяная компания мира задумалась об альтернативе для морских перевозок нефти14:56