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: w_3 -> s. p_9 <-> s. ~p_9.
p_9 -> s can be inferred via the biconditional elimination rule. s -> p_9 can be inferred via the biconditional elimination rule. ~s can be inferred via the biconditional elimination rule.