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: ~t_3. r_1 -> r. r_1 <-> q. r <-> t_3.
r_1 -> q can be inferred via the biconditional elimination rule. r -> t_3 can be inferred via the biconditional elimination rule. q -> r_1 can be inferred via the biconditional elimination rule. t_3 -> r can be inferred via the biconditional elimination rule. ~r can be inferred via the biconditional elimination rule.