What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y_4, if y_4 listens to a song, then y_4 is a writer. For all y_4, if y_4 were a writer, then y_4 is listening to a song. There is at least one y_4 for which if y_4 listens to a song, then y_4 is a writer.
For all y_4, y_4 will listen to a song if and only if y_4 is a writer. For all y_4, y_4 is a writer if and only if y_4 will listen to a song. There is at least one y_4 for which y_4 will listen to a song if and only if y_4 is a writer. There is at least one y_4 for which y_4 is a writer if and only if y_4 will listen to a song.