Consider the following premises. David is reading a book if and only if it is snowing. It is not snowing. Joseph is not sad. Joseph is sad 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 windy.
 From the fact that David is reading a book if and only if it is snowing, and that it is not snowing we can infer that David is not reading a book via biconditional elimination. Finally, from the fact that Joseph is sad if and only if it is windy, and that Joseph is not sad we can infer that it is not windy via biconditional elimination, which contradicts that It is windy. Therefore, the answer is no.