intros.
elim (EXPH4 (seq (ia Frame s3 (Tuple e1 d)) (K i))).
elim Lmers3.
elim LmerTnd.
elim LmerL.
elim LmerRn.
elim CommLRn.
elim CommTn_dL.
elim CommTn_dRn.
elim Comms3Tn_d.
elim Comms3L.
pattern e1 at 4 in |- *.
elimtype (toggle e0 = e1).
elim Comms3Rn_b.
repeat elim A6'.
elim Toggle1.
apply refl_equal.
elim Toggle1.
apply refl_equal.
Qed.

Theorem Lem17 :
forall d : D,
seq (ia D s4 d) (Y2 d) =
enc H
(mer (K i)
(mer (seq (ia D s4 d) (seq (ia frame s5 (tuple e1)) (R i)))
(mer (seq (Tn_d d e1) (S i)) (L i)))).