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. r <-> r_3. ~r_3.
r -> q can be inferred via the biconditional elimination rule. r -> r_3 can be inferred via the biconditional elimination rule. q -> r can be inferred via the biconditional elimination rule. r_3 -> r can be inferred via the biconditional elimination rule. ~r can be inferred via the biconditional elimination rule.