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 John were a taxi driver, then Jennifer is playing tennis. If Jennifer plays tennis, then Jessica is playing squash. If James were rich, then Jennifer is playing tennis. John is a taxi driver.
Jennifer is playing tennis can be inferred via the modus ponens rule. If John were a taxi driver, then Jessica is playing squash can be inferred via the transitivity rule. If James were rich, then Jessica is playing squash can be inferred via the transitivity rule.