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: t -> s. s -> q. w -> t. q -> w. ~q. q_3 <-> w.
~s can be inferred via the modus tollens rule. t -> q can be inferred via the transitivity rule. s -> w can be inferred via the transitivity rule. w -> s can be inferred via the transitivity rule. q -> t can be inferred via the transitivity rule. q_3 -> w can be inferred via the biconditional elimination rule. w -> q_3 can be inferred via the biconditional elimination rule.