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 z_1, if z_1 reads a book, then z_1 is a server. For all z_1, if z_1 were a server, then z_1 is reading a book. For all z_1, z_1 is a server or z_1 will not read a book.
For all z_1, if z_1 reads a book, then z_1 is a server can be inferred via the universal rewriting rule. For all z_1, z_1 will read a book if and only if z_1 is a server can be inferred via the universal biconditional introduction rule. For all z_1, z_1 is a server if and only if z_1 will read a book can be inferred via the universal biconditional introduction rule.