What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z_2, z_2 is a sailor if and only if z_2 is an office clerk. There is at least one z_2 for which z_2 is an office clerk if and only if z_2 will work.
For all z_2, if z_2 were a sailor, then z_2 is an office clerk. There is at least one z_2 for which if z_2 were an office clerk, then z_2 is working. For all z_2, if z_2 were an office clerk, then z_2 is a sailor. There is at least one z_2 for which if z_2 works, then z_2 is an office clerk.