How does set theory label chords?
A5: Chords are tagged by their “prime forms”, which is a set of numbers each of which corresponds to a pc (pitch class) or interval measured from a reference that is set to zero. Thus, CEG is 047. The prime form is the most compact representation of a set (normal form) with the first pc set to zero by transposition. Thus, GBDF (7B25), whose normal form is B257, becomes 0368 by transposition. Additionally, Allen Forte has created a system of set nomenclature called set names. See Introduction to Set Theory for more information.
