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: p_16 -> u. p_16 <-> w. u -> w. p_16 -> s_4. ~s_4.
~p_16 can be inferred via the modus tollens rule. p_16 -> w can be inferred via the transitivity rule. p_16 -> w can be inferred via the biconditional elimination rule. w -> p_16 can be inferred via the biconditional elimination rule.