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, if x_2 were rich, then x_2 is a doctor. For all x_2, if x_2 were a doctor, then x_2 is playing tennis. For all x_2, if x_2 plays tennis, then x_2 is rich.
For all x_2, if x_2 were rich, then x_2 is playing tennis can be inferred via the universal transitivity rule. For all x_2, if x_2 were a doctor, then x_2 is rich can be inferred via the universal transitivity rule. For all x_2, if x_2 plays tennis, then x_2 is a doctor can be inferred via the universal transitivity rule.