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_2 -> q_2. u_4 <-> w. q_2 -> u_4. w -> t_2. ~u_4.
~q_2 can be inferred via the modus tollens rule. t_2 -> u_4 can be inferred via the transitivity rule. w -> q_2 can be inferred via the transitivity rule. u_4 -> w can be inferred via the biconditional elimination rule. w -> u_4 can be inferred via the biconditional elimination rule. ~w can be inferred via the biconditional elimination rule.