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_9 <-> r. r_3 -> r. q_1 -> r_3.
q_1 -> r can be inferred via the transitivity rule. p_9 -> r can be inferred via the biconditional elimination rule. r -> p_9 can be inferred via the biconditional elimination rule.