Consider the following premises. Elisabeth is playing squash. If Elisabeth plays squash, then John is an artist. It is sunny if and only if John is an artist. Can we infer the following from them? It is sunny.
 From the fact that it is sunny if and only if John is an artist we can infer that if John were an artist, then it is sunny. From the fact that if Elisabeth plays squash, then John is an artist, and that if John were an artist, then it is sunny we can infer that if Elisabeth plays squash, then it is sunny. Finally, from the fact that if Elisabeth plays squash, then it is sunny, and that Elisabeth is playing squash we can infer that it is sunny. Therefore, the answer is yes.