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 David reads a book, then Michael is playing squash. David is reading a book or Michael is not playing squash. For all x_21, x_21 will read a book.
If Michael plays squash, then David is reading a book can be inferred via the rewriting rule.