What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_16, x_16 is a writer if and only if x_16 is a taxi driver. Joseph is a cashier if and only if Robert is not a taxi driver. Robert is not a writer.
If Joseph were a cashier, then Robert is not a taxi driver. If Robert were not a taxi driver, then Joseph is a cashier. For all x_16, if x_16 were a writer, then x_16 is a taxi driver. For all x_16, if x_16 were a taxi driver, then x_16 is a writer.