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I use earphones to listen to music. The cord connected to the earphones often gets entangled in my pocket and makes a knot, which I always find hard to untangle.

How can I define and calculate the probability that my cord spontaneously makes a knot?

Thank you.

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Thanks so much, that's what I'm looking for. If you post your comment as an answer I'll accept it. – pharmine Nov 8 '11 at 11:31
up vote 3 down vote accepted

Upon request I post my comment as an answer:

There is an interesting article on this topic by Dorian M. Raymer and Douglas E. Smith:

Spontaneous knotting of an agitated string

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