What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z, z is a carpenter or z is not a server. For all z, z is not a carpenter. For all z, z is a writer if and only if z is a server. For all z, if z were a server, then z is a writer.
For all z, if z were a server, then z is a carpenter. For all z, if z were a writer, then z is a server. For all z, if z were a server, then z is a writer.