∀ {α : Type u_1} (motive : RegularExpression α → Sort u_2) (h_1 : Unit → motive RegularExpression.zero)
  (h_2 : Unit → motive RegularExpression.epsilon) (h_3 : (a : α) → motive (RegularExpression.char a))
  (h_4 : (P Q : RegularExpression α) → motive (P.plus Q)) (h_5 : (P Q : RegularExpression α) → motive (P.comp Q))
  (h_6 : (P : RegularExpression α) → motive P.star),
  (match RegularExpression.zero with
    | RegularExpression.zero => h_1 ()
    | RegularExpression.epsilon => h_2 ()
    | RegularExpression.char a => h_3 a
    | P.plus Q => h_4 P Q
    | P.comp Q => h_5 P Q
    | P.star => h_6 P) =
    h_1 ()