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_4 <-> r_7. u -> p_4. p or u. ~p or r_7.
u or r_7 can be inferred via the resolution rule. p_4 -> r_7 can be inferred via the biconditional elimination rule. r_7 -> p_4 can be inferred via the biconditional elimination rule.