Consider the following premises. For all x_9, x_9 is not an electrician. For all x_9, x_9 is an electrician if and only if x_9 is a soldier. For all x_9, if x_9 were a soldier, then x_9 is a scientist. For all x_9, if x_9 were a scientist, then x_9 is a soldier. Can we infer the following from them? If we can, name the inference rule being used: For all x_9, x_9 is not a scientist.
 From the fact that for all x_9, x_9 is an electrician if and only if x_9 is a soldier we can infer that for all x_9, if x_9 were a soldier, then x_9 is an electrician via universal biconditional elimination. From the fact that for all x_9, if x_9 were a soldier, then x_9 is an electrician, and that for all x_9, x_9 is not an electrician we can infer that for all x_9, x_9 is not a soldier via universal modus tollens. From the fact that for all x_9, if x_9 were a soldier, then x_9 is a scientist, and that for all x_9, if x_9 were a scientist, then x_9 is a soldier we can infer that for all x_9, x_9 is a soldier if and only if x_9 is a scientist via universal biconditional introduction. Finally, from the fact that for all x_9, x_9 is a soldier if and only if x_9 is a scientist, and that for all x_9, x_9 is not a soldier we can infer that for all x_9, x_9 is not a scientist via universal biconditional elimination. Therefore, the answer is yes.