# Wikipedia Authors - NP (Complexity) (Highlights) ![rw-book-cover|256](https://readwise-assets.s3.amazonaws.com/static/images/article2.74d541386bbf.png) ## Highlights - NP is the [set](https://en.wikipedia.org/wiki/Set_(mathematics) "Set (mathematics)") of decision problems for which the [problem instances](https://en.wikipedia.org/wiki/Computational_complexity_theory#Problem_instances "Computational complexity theory"), where the answer is "yes", have [proofs](https://en.wikipedia.org/wiki/Mathematical_proof "Mathematical proof") verifiable in [polynomial time](https://en.wikipedia.org/wiki/Polynomial_time "Polynomial time") by a [deterministic Turing machine](https://en.wikipedia.org/wiki/Deterministic_Turing_machine "Deterministic Turing machine"). There exists a verifier which can checks a solution is correct in polynomial time. - the complexity class [co-NP](https://en.wikipedia.org/wiki/Co-NP "Co-NP") for which the answer "no" can be verified in polynomial time. Verifier which checks the answer is wrong in polynomial time