Consider the following premises. For all x_13, if x_13 plays tennis, then x_13 is sad. For all x_13, if x_13 were sad, then x_13 is playing tennis. For all x_13, x_13 will work if and only if x_13 will play tennis. For all x_13, x_13 will go running if and only if x_13 is sad. For all x_13, x_13 will not go running. Can we infer the following from them? There is at least one x_13 for which x_13 will work.
 From the fact that for all x_13, if x_13 were sad, then x_13 is playing tennis, and that for all x_13, if x_13 plays tennis, then x_13 is sad we can infer that for all x_13, x_13 is sad if and only if x_13 will play tennis. From the fact that for all x_13, x_13 will go running if and only if x_13 is sad we can infer that for all x_13, if x_13 were sad, then x_13 is running. From the fact that for all x_13, if x_13 were sad, then x_13 is running, and that for all x_13, x_13 will not go running we can infer that for all x_13, x_13 is not sad. From the fact that for all x_13, x_13 is sad if and only if x_13 will play tennis, and that for all x_13, x_13 is not sad we can infer that for all x_13, x_13 will not play tennis. Finally, from the fact that for all x_13, x_13 will work if and only if x_13 will play tennis, and that for all x_13, x_13 will not play tennis we can infer that for all x_13, x_13 will not work, which contradicts that There is at least one x_13 for which x_13 will work. Therefore, the answer is no.