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_4. u <-> w_4. p -> u.
u -> w_4 can be inferred via the biconditional elimination rule. w_4 -> u can be inferred via the biconditional elimination rule. ~u can be inferred via the biconditional elimination rule.