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. q -> r_6. u or u_4. q_2 or q. q_2 -> r_6. p -> ~u_4.
u_4 can be inferred via the disjunctive syllogism rule. r_6 can be inferred via the disjunction elimination rule.