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 -> p_8. q -> r. p_8 -> q. p_8 -> r.
r -> q can be inferred via the transitivity rule. q -> p_8 can be inferred via the transitivity rule. p_8 -> r can be inferred via the transitivity rule. r <-> p_8 can be inferred via the biconditional introduction rule. p_8 <-> r can be inferred via the biconditional introduction rule.