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_7 for which x_7 is a nurse. For all x_7, x_7 is a nurse if and only if x_7 will sleep. For all x_7, x_7 will not sleep.
Since the premises are contradictory, we can infer anything from them.