(* * Classical Natural Deduction *)
From Undecidability.FOL Require Export PCPb_to_FOL.
From Undecidability.Synthetic Require Import Definitions DecidabilityFacts EnumerabilityFacts ReducibilityFacts.
(* ** Double Negation Translation *)
Implicit Type b : falsity_flag.
Definition cprv := @prv _ _ falsity_on class.
Instance iUnit (P : Prop) : interp unit.

Lemma DN A phi :
A ⊢C (¬¬phi) -> A ⊢C phi.