Canonical extension: Difference between revisions

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(The page is marked as problematic because the definition of naturalness needs to be made more rigorous)
(The page is marked as problematic because the definition of naturalness needs to be made more rigorous)


Let ''T'' be a regular temperament on JI group ''G'' and let ''H'' be a JI group containing ''G'', but of one rank higher. The following are both informal concepts.
Consider a regular temperament on a JI group. The following are both informal concepts.
* A strong [[extension]] ''U'' on ''H'' is '''natural''' if the commas tempered out by ''T'' induce the presence of the added basis element of ''H''.
* A strong [[extension]] of said temperament on a JI group with one additional prime is '''natural''' if the commas tempered out by the temperament induce the presence of the added prime.
* A strong extension ''U'' on ''H'' is (more weakly) '''canonical''' if it is the most efficient (accurate and low-complexity) strong extension of ''T'' to ''H''.
* Such an extension is (more weakly) '''canonical''' if it is the most efficient (accurate and low-complexity) strong extension of the temperament to the larger subgroup.


== Examples ==
== Examples ==
=== Natural extensions ===
=== Natural extensions ===
* 5-limit Kleismic -> L5.13 Kleismic
* 5-limit Kleismic -> 2.3.5.13 Kleismic
* 5-limit Porcupine -> L5.11 Porcupine
* 5-limit Porcupine -> 2.3.5.11 Porcupine
=== Canonical but non-natural extensions ===
=== Canonical but non-natural extensions ===
* L5[81/80] -> L7[81/80, 126/125]
* 5-limit Meantone -> 7-limit Septimal Meantone (12 & 19)

Revision as of 02:54, 4 February 2026

This page or section is a work in progress. It may lack sufficient justification, content, or organization, and is subject to future overhaul.
This is a technical or mathematical page. While the subject may be of some relevance to music, the page treats the subject in technical language.

(The page is marked as problematic because the definition of naturalness needs to be made more rigorous)

Consider a regular temperament on a JI group. The following are both informal concepts.

  • A strong extension of said temperament on a JI group with one additional prime is natural if the commas tempered out by the temperament induce the presence of the added prime.
  • Such an extension is (more weakly) canonical if it is the most efficient (accurate and low-complexity) strong extension of the temperament to the larger subgroup.

Examples

Natural extensions

  • 5-limit Kleismic -> 2.3.5.13 Kleismic
  • 5-limit Porcupine -> 2.3.5.11 Porcupine

Canonical but non-natural extensions

  • 5-limit Meantone -> 7-limit Septimal Meantone (12 & 19)