What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Joseph plays squash, then Barbara is a scientist. Joseph is a doctor if and only if Barbara is a scientist. It is cold or Joseph is not a doctor.
If Joseph were a doctor, then it is cold. If Joseph were a doctor, then Barbara is a scientist. If Barbara were a scientist, then Joseph is a doctor.