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: ~p_7 or p_2. p_4 <-> p_2. p_7 or u_4. u_4 -> p_4.
u_4 or p_2 can be inferred via the resolution rule. p_4 -> p_2 can be inferred via the biconditional elimination rule. p_2 -> p_4 can be inferred via the biconditional elimination rule.