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 -> r_4. q_14. w -> r_4. w -> q_14. q_14 -> w.
w can be inferred via the modus ponens rule. q_14 -> r_4 can be inferred via the transitivity rule. w <-> q_14 can be inferred via the biconditional introduction rule. q_14 <-> w can be inferred via the biconditional introduction rule.