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