Corollary check_rval_wt:
  forall a x, wt_expr ce e a -> check_rval a = OK x -> wt_rvalue ce e a.Corollary check_lval_wt:
  forall a x, wt_expr ce e a -> check_lval a = OK x -> wt_lvalue ce e a.

Lemma wt_lred: forall tenv ge e a m a' m', lred ge e a m a' m' -> wt_lvalue ge tenv a -> wt_lvalue ge tenv a'.