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 \(\bar\gamma(s) := \gamma(1-s)\).
新华社3月7日报道，当日，数百名民众聚集在纽约市曼哈顿联合广场，高举伊朗国旗，手持“停止对伊朗战争”“不要插手伊朗”等标语，高呼“当今世界最大的威胁是特朗普和美国”。
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The weapons were never the real reason though, as Luis Rueda, head of the CIA's Iraq Operations Group at the time, told me later. "We would have invaded Iraq if Saddam Hussein had a rubber band and a paperclip. We would have said 'oh, he will take your eye out. Let's take him out.'"