Consider the following premises. If it is overcast, then it is raining. It is overcast if and only if it is cloudy. It is not cloudy. If it rains, then it is overcast. Can we infer the following from them? If we can, name the inference rule being used: It is raining.
 From the fact that if it is overcast, then it is raining, and that if it rains, then it is overcast we can infer that it is overcast if and only if it is raining via biconditional introduction. From the fact that it is overcast if and only if it is cloudy, and that it is not cloudy we can infer that it is not overcast via biconditional elimination. Finally, from the fact that it is overcast if and only if it is raining, and that it is not overcast we can infer that it is not raining via biconditional elimination, which contradicts that It is raining. Therefore, the answer is no.