What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z_4, if z_4 were a taxi driver, then z_4 is an electrician. For all z_4, if z_4 were a politician, then z_4 is a taxi driver. For all z_4, if z_4 were a taxi driver, then z_4 is a politician. There is at least one z_4 for which z_4 is not an electrician.
There is at least one z_4 for which z_4 is not a taxi driver. For all z_4, if z_4 were a politician, then z_4 is an electrician. For all z_4, z_4 is a politician if and only if z_4 is a taxi driver. For all z_4, z_4 is a taxi driver if and only if z_4 is a politician.