What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Robert takes a plane, then it is windy. It is snowing if and only if it is overcast. If it is not overcast, then Robert is taking a plane. It is not snowing.
If it is not overcast, then it is windy. If it snows, then it is overcast. If it is overcast, then it is snowing. It is not overcast.