Consider the following premises. ~R_12(a_12). forall x_12: R_12(x_12) or S_12(x_12). u_3. Can we infer S_12(a_12) and u_3 from them? If possible, name the inference rules being used at each step.
 From forall x_12: R_12(x_12) or S_12(x_12) we can infer R_12(a_12) or S_12(a_12) via universal instantiation. From R_12(a_12) or S_12(a_12), ~R_12(a_12) we can infer S_12(a_12) via disjunctive syllogism. Finally, from S_12(a_12), u_3 we can infer S_12(a_12) and u_3 via conjunction. Therefore, the answer is yes.