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_10, if x_10 takes a plane, then x_10 is playing squash. If Robert reads a book, then William is driving a car. If William drives a car, then Robert is taking a plane.
If Robert reads a book, then Robert is taking a plane can be inferred via the transitivity rule.