# constant structure

[Erv Wilson, via Kriag Grady, Yahoo Tuning List message 5244]

A tuning system where each interval occurs always subtended by the same number of steps. (THAT IS ALL, NO OTHER RESTRICTIONS)

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[Carl Lumma,Yahoo Tuning List message 5236]

A list of integers representing the cardinalities of nested MOS's is a Constant Structure of all scales that can support the entire nest. The larger the numbers, and the more of them, the fewer the number of scales in the Constant Structure (tho the number of scales is always infinite if you assume infinite tuning precision).

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[Carl Lumma,Yahoo Tuning List message 5250]

This was my stab at Lumma-CS, which we now know is not CS. It is a concept I got from Erv, tho; I wonder if he has a name for it?

...strict propriety does guarantee CS!

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[Paul Erlich,Yahoo Tuning List message 15405 Thu Nov 9, 2000 9:12pm]

Any periodicity block where the unison vectors are smaller than the smallest steps will be CS [constant structure].

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[Carl Lumma,Yahoo Tuning List message 53992, Mon Jul 5, 2004 12:23 am]

[Kraig Grady:]
I guess i would need an example of a Periodic block that was not a constant structure.
Here's one:
```1/1 135/128 9/8 5/4 45/32 3/2 27/16 15/8
```

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[Joe Monzo]

Below is a lattice-diagram of Carl's periodicity-block:

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