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_11, x_11 is not a janitor. For all x_11, x_11 is a janitor if and only if x_11 is a server. There is at least one x_11 for which x_11 is a server.
Since the premises are contradictory, we can infer anything from them.