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: u_2 -> r. u_2 <-> q_3. r -> q_3.
u_2 -> q_3 can be inferred via the transitivity rule. u_2 -> q_3 can be inferred via the biconditional elimination rule. q_3 -> u_2 can be inferred via the biconditional elimination rule.