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: If William were a taxi driver, then John is a doctor. If John were a doctor, then William is a politician. For all x_10, if x_10 were a politician, then x_10 is a taxi driver.
If William were a taxi driver, then William is a politician can be inferred via the transitivity rule.