English
Negation preserves primitive recursive predicates: if p is a primitive recursive predicate, then not p is also primitive recursive.
Русский
Отрицание примитивно вычисимого предиката также примитивно вычисимо.
LaTeX
$$$\\forall p:\\,\\alpha\\to\\mathrm{Prop},\\ PrimrecPred(p)\\to PrimrecPred(\\lambda a.\\neg p(a))$$$
Lean4
protected theorem _root_.PrimrecPred.not {p : α → Prop} : (hp : PrimrecPred p) → PrimrecPred fun a => ¬p a
| ⟨_, hp⟩ => Primrec.primrecPred <| Primrec.not.comp hp |>.of_eq <| by simp