Prolog Music Composer Reason for Intervals (Chord Progressions)

1564
semitone steps 2 7 8
or the ordered intervals between 1-5 (7), 5-6 (2) and 6-4 (8)

1645
semitone steps 2 8 9
or the ordered intervals between 1-6 (9), 6-4 (8) and 4-5 (2)

These steps are in ascending order so that the algorithm can find them.