What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Thomas were a doctor, then it is overcast. If it snows, then Thomas is a doctor. If it is overcast, then William is an electrician. If William were an electrician, then it is overcast.
If Thomas were a doctor, then William is an electrician. If it snows, then it is overcast. It is overcast if and only if William is an electrician. William is an electrician if and only if it is overcast.