Consider the following premises. If it is windy, then it is sunny. It is sunny if and only if it is snowing. If it snows, then it is windy. Can we infer the following from them? If we can, name the inference rule being used: It is windy if and only if it is sunny.
 From the fact that it is sunny if and only if it is snowing we can infer that if it is sunny, then it is snowing via biconditional elimination. From the fact that if it is sunny, then it is snowing, and that if it snows, then it is windy we can infer that if it is sunny, then it is windy via transitivity. Finally, from the fact that if it is windy, then it is sunny, and that if it is sunny, then it is windy we can infer that it is windy if and only if it is sunny via biconditional introduction. Therefore, the answer is yes.