Consider the following premises. Sarah is a cashier if and only if it is overcast. Susan is not a police officer. James is running if and only if it is overcast. If James goes running, then Susan is a police officer. Can we infer the following from them? If we can, name the inference rule being used: Sarah is a cashier.
 From the fact that if James goes running, then Susan is a police officer, and that Susan is not a police officer we can infer that James is not running via modus tollens. From the fact that James is running if and only if it is overcast, and that James is not running we can infer that it is not overcast via biconditional elimination. Finally, from the fact that Sarah is a cashier if and only if it is overcast, and that it is not overcast we can infer that Sarah is not a cashier via biconditional elimination, which contradicts that Sarah is a cashier. Therefore, the answer is no.