there are ways to convert problems within a computational complexity class. If you are interested in solving problem A, but only know how to solve problem B, you could try to convert A into a problem that is of type B.
If you efficiently solved the traveling salesmen problem, and you could convert the protein folding to a salesmen problem, you solved the protein folding.
One interesting question would be: are approximate solutions on the salesman also approximate solutions to the protein?
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