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 -> w. w -> s. r_2 -> q. s -> r_2.
u -> s can be inferred via the transitivity rule. w -> r_2 can be inferred via the transitivity rule. s -> q can be inferred via the transitivity rule.