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_10, if x_10 drinks water, then x_10 is reading a book. For all x_10, if x_10 reads a book, then x_10 is drinking water. There is at least one x_10 for which x_10 will drink water if and only if x_10 will read a book.
For all x_10, x_10 will drink water if and only if x_10 will read a book can be inferred via the universal biconditional introduction rule. For all x_10, x_10 will read a book if and only if x_10 will drink water can be inferred via the universal biconditional introduction rule. There is at least one x_10 for which if x_10 drinks water, then x_10 is reading a book can be inferred via the existential biconditional elimination rule. There is at least one x_10 for which if x_10 reads a book, then x_10 is drinking water can be inferred via the existential biconditional elimination rule.