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: There is at least one y_2 for which y_2 will play squash if and only if y_2 will cook. For all y_2, if y_2 cooks, then y_2 is playing a game. For all y_2, if y_2 reads a book, then y_2 is playing squash. For all y_2, if y_2 plays squash, then y_2 is reading a book.
For all y_2, y_2 will read a book if and only if y_2 will play squash can be inferred via the universal biconditional introduction rule. For all y_2, y_2 will play squash if and only if y_2 will read a book can be inferred via the universal biconditional introduction rule. There is at least one y_2 for which if y_2 plays squash, then y_2 is cooking can be inferred via the existential biconditional elimination rule. There is at least one y_2 for which if y_2 cooks, then y_2 is playing squash can be inferred via the existential biconditional elimination rule.