What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? q_1 <-> w. w -> q_1. ~r_2. q_1 -> r_2. r_2 -> q_1.
~q_1. w -> r_2. q_1 <-> r_2. r_2 <-> q_1. q_1 -> w. w -> q_1.