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_4, x_4 will not read a book. For all x_4, x_4 will read a book or x_4 is a cashier. There is at least one x_4 for which x_4 is a doctor.
For all x_4, x_4 is a cashier can be inferred via the universal disjunctive syllogism rule.