What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: forall x_9: R_9(x_9) <-> S_9(x_9). S_9(f_1) -> R_9(f_1).
forall x_9: R_9(x_9) -> S_9(x_9) can be inferred via the universal biconditional elimination rule. forall x_9: S_9(x_9) -> R_9(x_9) can be inferred via the universal biconditional elimination rule.