Consider the following premises. For all x_12, x_12 is not a musician. For all x_12, if x_12 were a cashier, then x_12 is not playing squash. For all x_12, x_12 is an office clerk or x_12 will play squash. For all x_12, if x_12 were an office clerk, then x_12 is writing a letter. For all x_12, x_12 will write a letter if and only if x_12 is a musician. Can we infer the following from them? There is at least one x_12 for which x_12 is a cashier.
 From the fact that for all x_12, x_12 will write a letter if and only if x_12 is a musician, and that for all x_12, x_12 is not a musician we can infer that for all x_12, x_12 will not write a letter. From the fact that for all x_12, if x_12 were an office clerk, then x_12 is writing a letter, and that for all x_12, x_12 will not write a letter we can infer that for all x_12, x_12 is not an office clerk. From the fact that for all x_12, x_12 is an office clerk or x_12 will play squash, and that for all x_12, x_12 is not an office clerk we can infer that for all x_12, x_12 will play squash. Finally, from the fact that for all x_12, if x_12 were a cashier, then x_12 is not playing squash, and that for all x_12, x_12 will play squash we can infer that for all x_12, x_12 is not a cashier, which contradicts that There is at least one x_12 for which x_12 is a cashier. Therefore, the answer is no.