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: s -> q_4. ~q_4. p_7 <-> w_1. ~p_7.
~s can be inferred via the modus tollens rule. ~q_4 and ~p_7 can be inferred via the conjunction rule. ~p_7 and ~q_4 can be inferred via the conjunction rule. p_7 -> w_1 can be inferred via the biconditional elimination rule. w_1 -> p_7 can be inferred via the biconditional elimination rule. ~w_1 can be inferred via the biconditional elimination rule.