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_12, if x_12 were a server, then x_12 is not a police officer. Jessica is a server if and only if Karen is poor. For all x_12, x_12 is a police officer.
If Jessica were a server, then Karen is poor can be inferred via the biconditional elimination rule. If Karen were poor, then Jessica is a server can be inferred via the biconditional elimination rule. For all x_12, x_12 is not a server can be inferred via the universal modus tollens rule.