33.5: Forte Numbers
33.5 Forte Numbers
When Allen Forte created a catalog of every possible 3-, 4-, 5-, 6-, 7-, 8-, and 9-note set in Appendix 1 of The Structure of Atonal Music, he labeled each prime form with two numbers separated by a hyphen. His labels (3–1, 3–2, etc.) are now known as “ Forte numbers ,” and are seen in the tables in the Lists of Set Classes , which include prime forms and interval vectors as well.
33.5.1 Z-Relations
“Z” in a set label (for example, 4–Z29) stands for “zygotic” (“twinned”), and is used when different prime forms (for example, 4–Z29 and 4–Z15 have the same interval vector—111111).