It is shown that if a generalized symmetric system is controllable on a neighborhood of a point, then the system is controllable on some open set which includes the group action-orbit at the point.

文中证明了如果广义对称系统在一点的邻域可控，那么系统在包含该点群作用轨道的一个开集上是可控的。

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The Orbit will only be open until 12 August.

BBC: Orbiting views of Olympic London

In July 2013, the Orbit is expected to re-open as a ticketed attraction with a cafe that can also host private functions.

BBC: Orbiting views of Olympic London

If Apophis passes the earth at a distance of exactly 18, 893 miles it will open a "gravitational keyhole" causing it to enter a new orbit that would put it on a direct collision course with earth seven years later.

CNN: Space's threat to civilization