Consider the following premises. It is snowing or it is not sunny. If it snows, then it is cloudy. If it is cloudy, then it is sunny. Can we infer the following from them? If we can, name the inference rule being used: It is cloudy if and only if it is snowing.
 From the fact that it is snowing or it is not sunny we can infer that if it is sunny, then it is snowing via rewriting. From the fact that if it is cloudy, then it is sunny, and that if it is sunny, then it is snowing we can infer that if it is cloudy, then it is snowing via transitivity. Finally, from the fact that if it is cloudy, then it is snowing, and that if it snows, then it is cloudy we can infer that it is cloudy if and only if it is snowing via biconditional introduction. Therefore, the answer is yes.