What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Charles were a writer, then Karen is listening to a song. Joseph is an electrician if and only if Karen is listening to a song. If Joseph were an electrician, then Charles is a writer.
If Joseph were an electrician, then Karen is listening to a song. If Joseph were an electrician, then Karen is listening to a song. If Karen listens to a song, then Joseph is an electrician.