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 y, y will play tennis or y will not read a book. There is at least one y for which y will work if and only if y will play tennis. For all y, if y works, then y is reading a book.
For all y, if y reads a book, then y is playing tennis can be inferred via the universal rewriting rule. There is at least one y for which if y works, then y is playing tennis can be inferred via the existential biconditional elimination rule. There is at least one y for which if y plays tennis, then y is working can be inferred via the existential biconditional elimination rule.