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: If Jennifer reads a book, then John is rich. John is not rich. For all x_9, x_9 will read a book if and only if x_9 will play tennis. If John were rich, then Jennifer is reading a book.
Jennifer is not reading a book can be inferred via the modus tollens rule. For all x_9, if x_9 reads a book, then x_9 is playing tennis can be inferred via the universal biconditional elimination rule. For all x_9, if x_9 plays tennis, then x_9 is reading a book can be inferred via the universal biconditional elimination rule.