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 it is cold, then it is cloudy. If it is cloudy, then Richard is working. If Richard works, then Susan is a taxi driver. Susan is not a taxi driver.
Richard is not working can be inferred via the modus tollens rule. If it is cold, then Richard is working can be inferred via the transitivity rule.