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_1. u_1 -> w. p or r_1. ~p.
w can be inferred via the modus ponens rule. r_1 can be inferred via the disjunctive syllogism rule. u_1 and ~p can be inferred via the conjunction rule. ~p and u_1 can be inferred via the conjunction rule.