Consider the following premises. For all x_15, if x_15 were fast, then x_15 is happy. For all x_15, x_15 will drive a car or x_15 is rich. For all x_15, x_15 is an office clerk if and only if x_15 is a doctor. For all x_15, if x_15 were rich, then x_15 is happy. For all x_15, if x_15 were happy, then x_15 is an office clerk. For all x_15, if x_15 drives a car, then x_15 is fast. Can we infer the following from them? For all x_15, x_15 is a doctor.
 From the fact that for all x_15, x_15 is an office clerk if and only if x_15 is a doctor we can infer that for all x_15, if x_15 were an office clerk, then x_15 is a doctor. From the fact that for all x_15, if x_15 drives a car, then x_15 is fast, and that for all x_15, if x_15 were fast, then x_15 is happy we can infer that for all x_15, if x_15 drives a car, then x_15 is happy. From the fact that for all x_15, if x_15 drives a car, then x_15 is happy, that for all x_15, if x_15 were rich, then x_15 is happy, and that for all x_15, x_15 will drive a car or x_15 is rich we can infer that for all x_15, x_15 is happy. From the fact that for all x_15, if x_15 were happy, then x_15 is an office clerk, and that for all x_15, x_15 is happy we can infer that for all x_15, x_15 is an office clerk. Finally, from the fact that for all x_15, if x_15 were an office clerk, then x_15 is a doctor, and that for all x_15, x_15 is an office clerk we can infer that for all x_15, x_15 is a doctor. Therefore, the answer is yes.