#[warning="-notation-incompatible-prefix"]
    Local Notation "R *" := (clos_refl_trans R)
      (at level 8, no associativity, format "R *").

Lemma clos_rstn1_sym : forall x y, clos_refl_sym_trans_n1 R x y -> clos_refl_sym_trans_n1 R y x.