What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Michael is a police officer if and only if John is a taxi driver. Michael is not a police officer. For all x_23, x_23 will not work. James is a nurse if and only if Elisabeth is working.
If Michael were a police officer, then John is a taxi driver. If James were a nurse, then Elisabeth is working. If John were a taxi driver, then Michael is a police officer. If Elisabeth works, then James is a nurse. John is not a taxi driver.