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_3 or q_15. w. q_15 -> r_15. w -> r_2. u_3 -> r_15.
r_2 can be inferred via the modus ponens rule. r_15 can be inferred via the disjunction elimination rule.