Consider the following premises. Mary is not reading a book. It is cloudy if and only if Mary is reading a book. Robert is a doctor. Can we infer the following from them? It is cloudy.
 From the fact that it is cloudy if and only if Mary is reading a book we can infer that if it is cloudy, then Mary is reading a book. Finally, from the fact that if it is cloudy, then Mary is reading a book, and that Mary is not reading a book we can infer that it is not cloudy, which contradicts that It is cloudy. Therefore, the answer is no.