Consider the following premises. It is late or Patricia is not reading a book. Patricia is reading a book if and only if Barbara is drinking water. Can we infer the following from them? If we can, name the inference rule being used: The fact that Barbara drinks water does not imply that it is late.
 From the fact that Patricia is reading a book if and only if Barbara is drinking water we can infer that if Barbara drinks water, then Patricia is reading a book via biconditional elimination. From the fact that it is late or Patricia is not reading a book we can infer that if Patricia reads a book, then it is late via rewriting. Finally, from the fact that if Barbara drinks water, then Patricia is reading a book, and that if Patricia reads a book, then it is late we can infer that if Barbara drinks water, then it is late via transitivity, which contradicts that The fact that Barbara drinks water does not imply that it is late. Therefore, the answer is no.