Glossary, Interval Content
Allen Forte’s interval content vectors nearly capture the internal structure of each set class but Lewin-Quinn FC components capture more information and use complementarity to group musical objects into fewer objects. (See Quinn’s master thesis in References.)
Each set class page (for example Major Triad and Diatonic) lists the interval content vector for that set class. From left to right, a vector tells how many of each of the six interval classes, semitone through tritone, are present in the set class.
In this example, <001110> means a major triad has one minor third, one major third, and one perfect fourth. Since a minor triad has the same intervals but in a different order, it is related by involution. The diatonic scale’s interval content vector, <254361>, means there are six perfect fourths/fifths, five whole tones, four minor thirds, three major thirds, two semitones, and one tritone.