Theorem 2 . Every orbit of the one-parameter subgroup of G is either a single point or a curve of constant ( geodesic ) curvature , and vice versa .
定理2在双曲平面H~2上,运动群G的单参数子群的每个轨道或是一个点,或是一条常(测地)曲率曲线.其逆亦真。