Consider the following premises. If Jennifer were a writer, then Charles is a poet. If it is overcast, then Jennifer is a writer. It is overcast or David is not a lawyer. If Charles were a poet, then David is a lawyer. Can we infer the following from them? If is not true that Charles is a poet if and only if it is overcast.
 From the fact that it is overcast or David is not a lawyer we can infer that if David were a lawyer, then it is overcast. From the fact that if it is overcast, then Jennifer is a writer, and that if Jennifer were a writer, then Charles is a poet we can infer that if it is overcast, then Charles is a poet. From the fact that if Charles were a poet, then David is a lawyer, and that if David were a lawyer, then it is overcast we can infer that if Charles were a poet, then it is overcast. Finally, from the fact that if Charles were a poet, then it is overcast, and that if it is overcast, then Charles is a poet we can infer that Charles is a poet if and only if it is overcast, which contradicts that If is not true that Charles is a poet if and only if it is overcast. Therefore, the answer is no.