What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? There is at least one y_3 for which if y_3 were a doctor, then y_3 is an office clerk. For all y_3, y_3 is a doctor if and only if y_3 is an office clerk. For all y_3, if y_3 were an office clerk, then y_3 is a doctor.
There is at least one y_3 for which y_3 is a doctor if and only if y_3 is an office clerk. There is at least one y_3 for which y_3 is an office clerk if and only if y_3 is a doctor. For all y_3, if y_3 were a doctor, then y_3 is an office clerk. For all y_3, if y_3 were an office clerk, then y_3 is a doctor.