Consider the following premises. Joseph is not playing tennis. For all x_4, x_4 will play tennis. Can we infer the following from them? If we can, name the inference rule being used: Joseph is an electrician.
 From the fact that for all x_4, x_4 will play tennis we can infer that for all x_4, x_4 will play tennis or x_4 is an electrician via universal addition. From the fact that for all x_4, x_4 will play tennis or x_4 is an electrician we can infer that Joseph is playing tennis or Joseph is an electrician via universal instantiation. Finally, from the fact that Joseph is playing tennis or Joseph is an electrician, and that Joseph is not playing tennis we can infer that Joseph is an electrician via disjunctive syllogism. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.