What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_2, x_2 will write a letter if and only if x_2 will read a book. William is not taking a plane. James is reading a book if and only if William is taking a plane.
If James reads a book, then William is taking a plane. If William takes a plane, then James is reading a book. James is not reading a book. For all x_2, if x_2 writes a letter, then x_2 is reading a book. For all x_2, if x_2 reads a book, then x_2 is writing a letter.