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_4 -> t. w_4 -> t. ~q_4. t -> q_4. s_4 -> w_4.
~t can be inferred via the modus tollens rule. w_4 -> q_4 can be inferred via the transitivity rule. s_4 -> t can be inferred via the transitivity rule. q_4 <-> t can be inferred via the biconditional introduction rule. t <-> q_4 can be inferred via the biconditional introduction rule.