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 bartender, then John is playing squash. If David were a taxi driver, then Linda is making tea. If David were not a taxi driver, then John is a bartender. Linda is not making tea.
David is not a taxi driver can be inferred via the modus tollens rule. If David were not a taxi driver, then John is playing squash can be inferred via the transitivity rule.