Inductive Sigma := embed (s : Sigma') | Start | hash.Inductive Sigma := embed (s : Sigma') | Start | hash.Inductive Sigma := embed (s : Sigma') | Start | hash.Inductive Sigma := embed (s : Sigma') | Start | hash.Definition embed_string (s : list Sigma') := map embed s.

Lemma terminal_f x : ~ Start el x <-> terminal (f P) x.