Consider the following premises. John is not excited. It is raining if and only if Jennifer is taking a plane. It is cold. Jennifer is taking a plane if and only if John is excited. Can we infer the following from them? If we can, name the inference rule being used: It is raining.
 From the fact that Jennifer is taking a plane if and only if John is excited, and that John is not excited we can infer that Jennifer is not taking a plane via biconditional elimination. Finally, from the fact that it is raining if and only if Jennifer is taking a plane, and that Jennifer is not taking a plane we can infer that it is not raining via biconditional elimination, which contradicts that It is raining. Therefore, the answer is no.