fact: Definition production_is_reachable {Char} (G : grammar Char) (p : production Char) : Prop := exists nt prefix, List.In nt (Valid_nonterminals G) /\ List.In (prefix ++ p) (Lookup G nt).
imports: Coq.Strings.String Coq.Lists.List Fiat.Parsers.StringLike.Core