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