Consider the following premises. For all y, if y makes tea, then y is reading a book. For all y, if y were a sailor, then y is reading a book. There is at least one y for which if y reads a book, then y is a sailor. For all y, y will not make tea. For all y, if y reads a book, then y is making tea. Can we infer the following from them? If we can, name the inference rule being used: For all y, y is a sailor.
 From the fact that there is at least one y for which if y reads a book, then y is a sailor, and that for all y, if y were a sailor, then y is reading a book we can infer that there is at least one y for which y will read a book if and only if y is a sailor via existential biconditional introduction. From the fact that for all y, if y reads a book, then y is making tea, and that for all y, if y makes tea, then y is reading a book we can infer that for all y, y will read a book if and only if y will make tea via universal biconditional introduction. From the fact that for all y, y will read a book if and only if y will make tea, and that for all y, y will not make tea we can infer that for all y, y will not read a book via universal biconditional elimination. Finally, from the fact that there is at least one y for which y will read a book if and only if y is a sailor, and that for all y, y will not read a book we can infer that there is at least one y for which y is not a sailor via existential biconditional elimination, which contradicts that For all y, y is a sailor. Therefore, the answer is no.