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 David were a doctor, then it is cloudy. It is not cloudy. Susan is a poet.
David is not a doctor can be inferred via the modus tollens rule. It is not cloudy and Susan is a poet can be inferred via the conjunction rule. Susan is a poet and it is not cloudy can be inferred via the conjunction rule.