Similarly, every Π 1 0 {\displaystyle \Pi _{1}^{0}} set is closed and the Π 1 0 {\displaystyle \Pi _{1}^{0}} sets are sometimes called effectively closed.
Слично томе, сваки  Π 1 0 {\displaystyle \Pi _{1}^{0}}  скуп је затворен и  Π 1 0 {\displaystyle \Pi _{1}^{0}}  скупови се понекад називају затвореним.