The geometry of music. The Neo-Riemannian theory, which is a topic in music theory that gives some insight into progressions of major and minor triad chords https://plus.google.com/u...
"A group in mathematics is an object that measures symmetry in the same way that a number measures quantity, groups can be used to cast light on Neo-Riemannian theory" More: http://en.wikipedia.org/wiki... // "The red lines connect notes that are a major third apart. The green lines connect notes that are a minor third apart. The blue lines connect notes that are a perfect fifth apart. Each triangle is a chord with three notes, called a triad. These are the most basic chords in Western music. There are two kinds: A major triad sounds happy. The major triads are the triangles whose edges go red-green-blue as you go around clockwise. A minor triad sounds sad. The minor triads are the triangles whose edges go green-red-blue as you go around clockwise. This pattern is called a tone net, and this one was created by David W. Bulger." https://plus.google.com/u... - Amira