What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Barbara is not a scientist. If Barbara were a scientist, then it is late. If it is overcast, then Barbara is a scientist. If it is late, then it is overcast.
It is not overcast. If Barbara were a scientist, then it is overcast. If it is overcast, then it is late. If it is late, then Barbara is a scientist.