Consider the following premises. Elisabeth is not a soldier. For all z_4, z_4 is an office clerk if and only if z_4 is a soldier. Can we infer the following from them? If we can, name the inference rule being used: Elisabeth is an office clerk.
 From the fact that for all z_4, z_4 is an office clerk if and only if z_4 is a soldier we can infer that Elisabeth is an office clerk if and only if Elisabeth is a soldier via universal instantiation. Finally, from the fact that Elisabeth is an office clerk if and only if Elisabeth is a soldier, and that Elisabeth is not a soldier we can infer that Elisabeth is not an office clerk via biconditional elimination, which contradicts that Elisabeth is an office clerk. Therefore, the answer is no.