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 Barbara drives a car, then it is overcast. If John were a doctor, then Charles is sleeping. John is a doctor. If Charles sleeps, then it is overcast.
Charles is sleeping can be inferred via the modus ponens rule. If John were a doctor, then it is overcast can be inferred via the transitivity rule.