Glossary of scale properties: Difference between revisions
→Properties: DE should be generalized to arbitrary arity; DE isn't a commonly used synonym of MOS, anyway. |
remove duplicate MOS entry |
||
| Line 32: | Line 32: | ||
: A scale is symmetrical if at least one mode of the scale is symmetrical. Therefore, every interval of that mode must have an inverse. These scales will always have an odd number of notes ''per period''. They may not always have an odd number of notes ''per octave'', however. The diatonic scale is symmetrical, but so is 12edo. | : A scale is symmetrical if at least one mode of the scale is symmetrical. Therefore, every interval of that mode must have an inverse. These scales will always have an odd number of notes ''per period''. They may not always have an odd number of notes ''per octave'', however. The diatonic scale is symmetrical, but so is 12edo. | ||
; | ; Myhill's property and MOS | ||
* '''Myhill's property''': A scale has Myhill's property if there are exactly two interval sizes for each generic interval class (except octaves or other equivalence intervals such as tritaves). | * '''Myhill's property''': A scale has Myhill's property if there are exactly two interval sizes for each generic interval class (except octaves or other equivalence intervals such as tritaves). | ||
* '''Trivalence property''': Same as Myhill's property, but replace "two interval sizes" with "three interval sizes." The scale formed from the notes of a dominant 7th chord (e.g. C-E-G-Bb-C) is an example of a trivalent scale. | * '''Trivalence property''': Same as Myhill's property, but replace "two interval sizes" with "three interval sizes." The scale formed from the notes of a dominant 7th chord (e.g. C-E-G-Bb-C) is an example of a trivalent scale. | ||
* '''[[Moment of symmetry]]''': Both | * '''[[MOS|Moment of symmetry (MOS)]]''': A scale is a MOS scale if there are no more than two interval sizes for each generic interval class (e.g. major/minor thirds, perfect/augmented fourths, etc). Both [[distributional evenness|distributionally even]] and Myhill's are essentially synonymous with MOS; Myhill's property is sometimes called "strict MOS". | ||
The 12-tone diatonic scale has Myhill's property, and is also distributionally even. | The 12-tone diatonic scale has Myhill's property, and is also distributionally even. | ||
| Line 57: | Line 56: | ||
[[Category:Scale]] | [[Category:Scale]] | ||
[[Category:Todo:add examples]] | [[Category:Todo:add examples]] | ||
[[Category:Todo:add illustration]] | [[Category:Todo:add illustration]] | ||