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_expression_meets_spec: forall r g s a g' I, transl_expression r g = Res (s, a) g' I -> tr_expression r s a.