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: q_8 -> s. w <-> s. w -> q_8.
w -> s can be inferred via the transitivity rule. w -> s can be inferred via the biconditional elimination rule. s -> w can be inferred via the biconditional elimination rule.