What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_1, if x_1 were a nurse, then x_1 is a server. For all x_1, if x_1 were a server, then x_1 is a nurse.
For all x_1, x_1 is a nurse if and only if x_1 is a server. For all x_1, x_1 is a server if and only if x_1 is a nurse.