proposition: Lemma remove_nonterminal_5 {ls ps ps'} (H0 : ps <> ps') : is_valid_nonterminal (remove_nonterminal ls ps) ps' = is_valid_nonterminal ls ps'.
proof: Proof. case_eq (is_valid_nonterminal (remove_nonterminal ls ps) ps'); case_eq (is_valid_nonterminal ls ps'); intros H' H''; try reflexivity; exfalso; first [ apply remove_nonterminal_1 in H'' | apply remove_nonterminal_2 in H''; destruct H''; subst ]; congruence. Qed.
imports: Fiat.Common.Coq__8_4__8_5__Compat Coq.Classes.RelationClasses Coq.Setoids.Setoid Coq.ZArith.ZArith Fiat.Parsers.ContextFreeGrammar.Core Fiat.Parsers.BaseTypes