coNP
定義
$ \textbf{coNP} := \overline{\mathbf{NP}}
または
$ x \in L \iff \forall u \in 2^{p(|x|)}. [M(\langle x, u \rangle) = 1]
性質
$ \textbf{P} \subseteq \textbf{NP} \cap \textbf{coNP}
Proof. $ p(x) = 0❏
$ \textbf{P} = \textbf{NP} \Rightarrow \textbf{NP} = \textbf{coNP}
Proof. $ L \in \textbf{coNP} \iff \bar{L} \in \textbf{NP} \iff \bar{L} \in \textbf{P} \iff L \in \textbf{P} \iff L \in \textbf{NP} ❏