Scheme expr_ind2 := Induction for Csyntax.expr Sort Prop
with exprlist_ind2 := Induction for Csyntax.exprlist Sort Prop.
Combined Scheme expr_exprlist_ind from expr_ind2, exprlist_ind2.

Lemma transl_if_meets_spec:
forall r s1 s2 g s g' I,
transl_if r s1 s2 g = Res s g' I ->
tr_if r s1 s2 s.