What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: For all x_6, x_6 will read a book. For all x_6, x_6 is a server or x_6 is a police officer. For all x_6, if x_6 were a server, then x_6 is not reading a book.
For all x_6, x_6 is not a server can be inferred via the universal modus tollens rule.