Assume you are a superman who is very elastic, after making linked rings with your index fingers and thumbs, could you move your hands apart without separating the joined fingertips?
In other words, is it possible to go from (a) to (b) without “breaking” the figure above?
Figure taken from Intuitive Topology (Mathematical World, Vol 4).
The answer is yes!
This is an animation of the solution: https://vk.com/video-9666747_142799479