What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, if x_4 reads a book, then x_4 is taking a plane. There is at least one x_4 for which x_4 will not read a book. For all x_4, x_4 will take a plane if and only if x_4 will read a book.
For all x_4, if x_4 takes a plane, then x_4 is reading a book. For all x_4, if x_4 reads a book, then x_4 is taking a plane. There is at least one x_4 for which x_4 will not take a plane.