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_3. p_8 -> w. s_3 -> p_8. p_8 <-> u_3. w -> s_3.
~w can be inferred via the modus tollens rule. p_8 -> s_3 can be inferred via the transitivity rule. s_3 -> w can be inferred via the transitivity rule. w -> p_8 can be inferred via the transitivity rule. p_8 -> u_3 can be inferred via the biconditional elimination rule. u_3 -> p_8 can be inferred via the biconditional elimination rule.