Consider the following premises. For all x_4, if x_4 climbs a mountain, then x_4 is an electrician. For all x_4, if x_4 were an electrician, then x_4 is climbing a mountain. For all x_4, x_4 will play tennis. There is at least one x_4 for which if x_4 climbs a mountain, then x_4 is not playing tennis. Can we infer the following from them? There is at least one x_4 for which x_4 is not an electrician.
 From the fact that there is at least one x_4 for which if x_4 climbs a mountain, then x_4 is not playing tennis, and that for all x_4, x_4 will play tennis we can infer that there is at least one x_4 for which x_4 will not climb a mountain. From the fact that for all x_4, if x_4 were an electrician, then x_4 is climbing a mountain, and that for all x_4, if x_4 climbs a mountain, then x_4 is an electrician we can infer that for all x_4, x_4 is an electrician if and only if x_4 will climb a mountain. Finally, from the fact that for all x_4, x_4 is an electrician if and only if x_4 will climb a mountain, and that there is at least one x_4 for which x_4 will not climb a mountain we can infer that there is at least one x_4 for which x_4 is not an electrician. Therefore, the answer is yes.