What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If it is late, then Sarah is a doctor. For all x_15, if x_15 were a soldier, then x_15 is a doctor. For all x_15, x_15 is a doctor if and only if x_15 is a soldier. Sarah is not a soldier.
For all x_15, if x_15 were a doctor, then x_15 is a soldier. For all x_15, if x_15 were a soldier, then x_15 is a doctor.