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integer power

For a group element $a$ and integer $n$ , the result $a^n$ of combining $a$ with itself $n$ times ( $n>0$ ), its inverse $n$ times ( $n<0$ ), or the identity ( $n=0$ ).

Examples

In $D_4$ , $r^2$ is the 180-degree rotation; $r^{-1}$ is that same rotation run backward.