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This is a list of set classes, by Forte number. A set class (an abbreviation of pitch-class-set class) in music theory is an ascending collection of pitch classes, transposed to begin at zero. For a list of ordered collections, see: list of tone rows and series.

Sets are listed with links to their complements. The prime form of unsymmetrical sets is marked "A". Inversions are marked "B" (sets not marked "A" or "B" are symmetrical). "T" and "E" are conventionally used in sets to notate ten and eleven, respectively, as single characters. The ordering of sets in the lists is based on the string of numerals in the interval vector treated as an integer, decreasing in value, following the strategy used by Forte in constructing his numbering system. Numbers marked with a "Z" refer to a pair of different set classes with identical interval class content that are not related by inversion, with one of each pair listed at the end of the respective list when they occur.

There are two slightly different methods of obtaining the prime form—an earlier one due to Allen Forte and a later (and generally now more popular) one devised by John Rahn—both often confusingly described as "most packed to the left". However, a more precise description of the Rahn spelling is to select the version that is most dispersed from the right. The precise description of the Forte spelling is to select the version that is most packed to the left within the smallest span. This results in two different prime form sets for the same Forte number in a number of cases. The lists here use the Rahn spelling. The alternative notations for those set classes where the Forte spelling differs are listed in the footnotes.

Elliott Carter had earlier (1960–67) produced a numbered listing of pitch class sets, or "chords", as Carter referred to them, for his own use. Donald Martino had produced tables of hexachords, tetrachords, trichords, and pentachords for combinatoriality in his article, "The Source Set and its Aggregate Formations" (1961).

The difference between the interval vector of a set and that of its complement is <X, X, X, X, X, X/2>, where (in base-ten) X = 12 – 2C, and C is the cardinality of the smaller set. In nearly all cases, complements of unsymmetrical sets are inversionally related—i.e. the complement of an "A" version of a set of cardinality C is (usually) the "B" version of the respective set of cardinality 12 – C. The most significant exceptions are the sets 4-14/8-14, 5-11/7-11, and 6-14, which are all closely related in terms of subset/superset structure.

List

There is an anomaly in Allen Forte's book concerning the numbering of the pair of hexachords 6-Z28, , and 6-Z49, , where adjacency intervals are shown here by subscripts. They both have the same span, with a minor-third at the right. But, within that span, the hexachord is "more packed to the left" than , as seen by inspecting the left-hand adjacency-interval sequences, and therefore, according to Forte's own rule, the set should have been assigned the lower number 6-Z28, with given the higher number 6-Z49.

See also

• Interval vector
• List of chords
• Z-relation

References

Notes

1. Forte and Rahn both list prime forms as the most left-packed possible version of a set. However, Forte packs from the left and Rahn packs from the right ("making the small numbers smaller," versus making, "the larger numbers ... smaller").
2. Forte 5-20A:
3. Forte 5-20B:
4. Forte 5-32B:
5. Forte 6-Z29:
6. Forte 6-31A:
7. Forte 6-31B:
8. Forte 6-Z44B:
9. Forte 7-Z18A:
10. Forte 7-Z18B:
11. Forte 7-20A:
12. Forte 7-20B:
13. Forte 8-22B:
14. Forte 8-26:
15. Forte 8-27B:
16. Forte 9-7B:
17. Forte 9-8B:
18. Forte 9-11B:

Sources

1. Forte, Allen (1973). The Structure of Atonal Music. Yale University Press. ISBN 0-300-02120-8.
2. Nelson, Paul (2004). "Two Algorithms for Computing the Prime Form", ComposerTools.com.
3. Rahn, John (1980). Basic Atonal Theory. New York: Longman. ISBN 978-0028731605.
4. Straus, Joseph N. (1990). Introduction to Post-Tonal Theory. Prentice-Hall. ISBN 9780131898905.
5. Schiff, David (1983/1998). The Music of Elliott Carter.
6. Carter, Elliott (2002). The Harmony Book, "Appendix 1". ISBN 9780825845949.
7. Schuijer, Michael (2008). Analyzing Atonal Music: Pitch-Class Set Theory and Its Contexts, p.97. University of Rochester. ISBN 978-1-58046-270-9.
8. Everett, Walter (2008). The Foundations of Rock, p.169. Oxford. ISBN 9780199718702.

External links

• Pitch Class Set Calculator from Mount Allison University
• Chord Analyzer on Lamadeguido.com

Online lists

• Solomon, Larry (2005). "The Table of Pitch Class Sets", SolomonsMusic.net.
• Tucker, Gary (2001). "Table of pc set classes", A Brief Introduction to Pitch-Class Set Analysis.
• Nelson, Paul (2004). "Table of Prime Forms", ComposerTools.com.

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