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: r <-> q_3. ~r. q_3 <-> u.
r -> q_3 can be inferred via the biconditional elimination rule. q_3 -> u can be inferred via the biconditional elimination rule. q_3 -> r can be inferred via the biconditional elimination rule. u -> q_3 can be inferred via the biconditional elimination rule. ~q_3 can be inferred via the biconditional elimination rule.