## complementary nondeterministic polynomial

(complexity) (Co-NP) The set (or property) of problems with a yes/no answer where the complementary no/yes problem takes nondeterministic polynomial time (NP).

For example, "Is n prime" is Co-NP and "Is n not prime" is NP, since it is only necessary to find one factor to prove that n is not prime whereas to prove that it is prime all possible factors must be eliminated.

Last updated: 2009-05-21

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