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: There is at least one x_8 for which x_8 is a police officer if and only if x_8 is a server. For all x_8, if x_8 were a server, then x_8 is a scientist. For all x_8, if x_8 were a scientist, then x_8 is a police officer.
For all x_8, if x_8 were a server, then x_8 is a police officer can be inferred via the universal transitivity rule. There is at least one x_8 for which if x_8 were a police officer, then x_8 is a server can be inferred via the existential biconditional elimination rule. There is at least one x_8 for which if x_8 were a server, then x_8 is a police officer can be inferred via the existential biconditional elimination rule.