coNP ⊆ PSPACE

Inclusion · folklore

Statement

coNP $\subseteq$ PSPACE — folklore.

Sketch

$\mathbf{NP}\subseteq \mathbf{PSPACE}$ by enumerating all candidate certificates in reused space (NP ⊆ PSPACE), and $\mathbf{PSPACE}$ is closed under complement.