Consider the following premises. For all x_7, x_7 will write a letter or x_7 is not a scientist. For all x_7, x_7 is a scientist or x_7 will not write a letter. Can we infer the following from them? If we can, name the inference rule being used: For all x_7, if x_7 writes a letter, then x_7 is a scientist.
 From the fact that for all x_7, x_7 will write a letter or x_7 is not a scientist we can infer that for all x_7, if x_7 were a scientist, then x_7 is writing a letter via universal rewriting. Finally, from the fact that for all x_7, x_7 is a scientist or x_7 will not write a letter we can infer that for all x_7, if x_7 writes a letter, then x_7 is a scientist via universal rewriting. Therefore, the answer is yes.