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_2, x_2 is a taxi driver or x_2 is rich. There is at least one x_2 for which x_2 will not sleep. For all x_2, if x_2 were a taxi driver, then x_2 is sleeping.
There is at least one x_2 for which x_2 is not a taxi driver can be inferred via the existential modus tollens rule.