What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Charles is writing a letter or Jessica is a poet. If Richard listens to a song, then Charles is writing a letter. If Jessica were a poet, then Richard is listening to a song. If Charles writes a letter, then Richard is listening to a song.
If Jessica were a poet, then Charles is writing a letter. Richard is listening to a song. Richard is listening to a song if and only if Charles is writing a letter. Charles is writing a letter if and only if Richard is listening to a song.