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_4. s -> ~q_11. q_11. s <-> q_4.
~s can be inferred via the modus tollens rule. p_4 and q_11 can be inferred via the conjunction rule. q_11 and p_4 can be inferred via the conjunction rule. s -> q_4 can be inferred via the biconditional elimination rule. q_4 -> s can be inferred via the biconditional elimination rule.