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_18, x_18 is rich. For all x_18, x_18 will sleep if and only if x_18 is rich. There is at least one x_18 for which x_18 will not play a game. For all x_18, x_18 will sleep if and only if x_18 will play a game.
Since the premises are contradictory, we can infer anything from them.