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: ~u. q_1 -> w. w <-> u. p_1 -> q_1.
p_1 -> w can be inferred via the transitivity rule. w -> u can be inferred via the biconditional elimination rule. u -> w can be inferred via the biconditional elimination rule. ~w can be inferred via the biconditional elimination rule.