设 P和 Q为平面内两个互不相交的简单多边形 ，若 P在平面内绕某点旋转 ，文中讨论了其旋转可移动性问题 。
Let P and Q be two nonintersecting simple polygons in the plane, this paper discusses the rotational movability of them if P rotates around a point and collides with Q .
一个飞盘是有边缘，所以可以，让它绕着边缘上某点旋转，就像这样，绕边缘点转动它。
A Frisbee has this rim so you can actually try to make it rotate around the point on the circumference by holding it near the rim and spinning it there.
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