Consider the following premises. For all x_13, x_13 is a soldier if and only if x_13 will drink water. For all x_13, x_13 is not a soldier. For all x_13, x_13 will drink water if and only if x_13 is an electrician. For all x_13, x_13 is an electrician or x_13 will not drink water. Can we infer the following from them? If we can, name the inference rule being used: For all x_13, x_13 is not an electrician.
 From the fact that for all x_13, x_13 will drink water if and only if x_13 is an electrician we can infer that for all x_13, if x_13 were an electrician, then x_13 is drinking water via universal biconditional elimination. From the fact that for all x_13, x_13 is an electrician or x_13 will not drink water we can infer that for all x_13, if x_13 drinks water, then x_13 is an electrician via universal rewriting. From the fact that for all x_13, x_13 is a soldier if and only if x_13 will drink water, and that for all x_13, x_13 is not a soldier we can infer that for all x_13, x_13 will not drink water via universal biconditional elimination. From the fact that for all x_13, if x_13 drinks water, then x_13 is an electrician, and that for all x_13, if x_13 were an electrician, then x_13 is drinking water we can infer that for all x_13, x_13 will drink water if and only if x_13 is an electrician via universal biconditional introduction. Finally, from the fact that for all x_13, x_13 will drink water if and only if x_13 is an electrician, and that for all x_13, x_13 will not drink water we can infer that for all x_13, x_13 is not an electrician via universal biconditional elimination. Therefore, the answer is yes.