Consider the following premises. If it is sunny, then it is windy. If it is windy, then it is sunny. It is not windy. Can we infer the following from them? It is not sunny or Elisabeth is writing a letter.
 From the fact that if it is sunny, then it is windy, and that if it is windy, then it is sunny we can infer that it is sunny if and only if it is windy. From the fact that it is sunny if and only if it is windy, and that it is not windy we can infer that it is not sunny. Finally, from the fact that it is not sunny we can infer that it is not sunny or Elisabeth is writing a letter. Therefore, the answer is yes.