What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x, x is an artist if and only if x is a taxi driver. If Joseph were an artist, then Robert is running. Robert is running if and only if Joseph is a taxi driver.
If Robert goes running, then Joseph is a taxi driver. If Joseph were a taxi driver, then Robert is running. For all x, if x were an artist, then x is a taxi driver. For all x, if x were a taxi driver, then x is an artist.