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_3, if y_3 reads a book, then y_3 is a server. For all y_3, y_3 is not a scientist. There is at least one y_3 for which if y_3 reads a book, then y_3 is a server. For all y_3, if y_3 reads a book, then y_3 is a scientist. For all y_3, if y_3 were a server, then y_3 is reading a book.
For all y_3, y_3 will not read a book can be inferred via the universal modus tollens rule. For all y_3, if y_3 were a server, then y_3 is a scientist can be inferred via the universal transitivity rule. For all y_3, y_3 will read a book if and only if y_3 is a server can be inferred via the universal biconditional introduction rule. For all y_3, y_3 is a server if and only if y_3 will read a book can be inferred via the universal biconditional introduction rule. There is at least one y_3 for which y_3 will read a book if and only if y_3 is a server can be inferred via the existential biconditional introduction rule. There is at least one y_3 for which y_3 is a server if and only if y_3 will read a book can be inferred via the existential biconditional introduction rule.