proposition: Lemma positive_to_nonterminal_eq x y : positive_to_nonterminal x = positive_to_nonterminal y <-> x = y.
proof: Proof. split; try congruence. rewrite <- (positive_to_nonterminal_to_positive x), <- (positive_to_nonterminal_to_positive y) at 2. congruence. Qed.
imports: Coq.PArith.BinPos Coq.PArith.Pnat Coq.Arith.Arith Coq.FSets.FMapInterface Coq.FSets.FMapPositive Fiat.Parsers.ContextFreeGrammar.Carriers Fiat.Common.List.ListFacts Fiat.Common.List.ListMorphisms Fiat.Common.Prod