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. w. u_4 -> q. q <-> s.
~s and w can be inferred via the conjunction rule. w and ~s can be inferred via the conjunction rule. q -> s can be inferred via the biconditional elimination rule. s -> q can be inferred via the biconditional elimination rule. ~q can be inferred via the biconditional elimination rule.