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_2, z_2 is not a server. For all z_2, z_2 is a server. There is at least one z_2 for which z_2 is an office clerk.
Since the premises are contradictory, we can infer anything from them.