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: q -> w. w -> q. w_3 <-> q.
q <-> w can be inferred via the biconditional introduction rule. w <-> q can be inferred via the biconditional introduction rule. w_3 -> q can be inferred via the biconditional elimination rule. q -> w_3 can be inferred via the biconditional elimination rule.