Consider the following premises. If Patricia reads a book, then Sarah is curious. Patricia is reading a book or it is not overcast. If Sarah were curious, then it is overcast. Can we infer the following from them? If we can, name the inference rule being used: If is not true that Patricia is reading a book if and only if it is overcast.
 From the fact that if Patricia reads a book, then Sarah is curious, and that if Sarah were curious, then it is overcast we can infer that if Patricia reads a book, then it is overcast via transitivity. From the fact that Patricia is reading a book or it is not overcast we can infer that if it is overcast, then Patricia is reading a book via rewriting. Finally, from the fact that if Patricia reads a book, then it is overcast, and that if it is overcast, then Patricia is reading a book we can infer that Patricia is reading a book if and only if it is overcast via biconditional introduction, which contradicts that If is not true that Patricia is reading a book if and only if it is overcast. Therefore, the answer is no.