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. ~q -> w_2. w_2 or ~w_4. w <-> q.
w_4 -> w_2 can be inferred via the rewriting rule. w -> q can be inferred via the biconditional elimination rule. q -> w can be inferred via the biconditional elimination rule. ~q can be inferred via the biconditional elimination rule.