Consider the following premises. Robert is reading a book if and only if David is a writer. For all y, y will not read a book. David is a writer if and only if it is windy. Can we infer the following from them? If we can, name the inference rule being used: It is not windy.
 From the fact that for all y, y will not read a book we can infer that Robert is not reading a book via universal instantiation. From the fact that Robert is reading a book if and only if David is a writer, and that Robert is not reading a book we can infer that David is not a writer via biconditional elimination. Finally, from the fact that David is a writer if and only if it is windy, and that David is not a writer we can infer that it is not windy via biconditional elimination. Therefore, the answer is yes.