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 carpenter. For all x_8, if x_8 were a carpenter, then x_8 is not sad. For all x_8, x_8 is a taxi driver. For all x_8, if x_8 were a taxi driver, then x_8 is sad.
Since the premises are contradictory, we can infer anything from them.