(*  a -->  b -->* c    d - by prior lemma |      |      |    e - by induction. v      v      v *      *      * a2 --> d -->* e  *)

Lemma multipar_confluence : forall S D a a1, Good S D -> erased_tm a -> multipar S D a a1
-> forall a2, multipar S D a a2 -> exists b, multipar S D a1 b /\ multipar S D a2 b.