What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? w_4 -> r_1. ~r. r_4 -> w_4. r <-> r_4. r_1 -> r_4.
w_4 -> r_4. r_4 -> r_1. r_1 -> w_4. r -> r_4. r_4 -> r. ~r_4.