Probabilistically checkable proofs give rise to many complexity classes depending on the number of queries required and the amount of randomness used. The class PCP["r"("n"),"q"("n")] refers to the set of decision problems that have probabilistically checkable proofs that can be verified in polynomial time using at most "r"("n") random bits and by reading at most "q"("n") bits of the proof. Unless specified otherwise, correct proofs should always be accepted, and incorrect proofs should be rejected with probability greater than 1/2. The PCP theorem, a major result in computational complexity theory, states that PCP"n"),O(1) = NP.