Distributional evenness: Difference between revisions

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{{Distinguish|Maximal evenness}}
{{Distinguish|Maximal evenness}}
A scale with two step sizes is '''distributionally even''' ('''DE''') if it has its two step sizes distributed as evenly as possible (i.e. each step size is distributed in a [[maximal evenness|maximally even]] pattern among the steps of the scale). This turns out to be equivalent to the property of having [[maximum variety]] 2; that is, each [[interval class]] ("seconds", "thirds", and so on) contains no more than two sizes. Though the term as originally defined is limited to scales with two step sizes, distributional evenness has an obvious generalization to scales of arbitrary [[arity]]: we simply require that each of the three or more step sizes be evenly distributed.
A scale is '''distributionally even''' if equating all step sizes except one will always result in a MOS. MOSses are the only distributionally even binary scales. The term was originally defined as a generalization of [[maximal evenness]] specifically for binary scales; this is the most convenient generalization.


In practice, binary DE scales are often referred to as "[[MOS scale]]s", but some consider this usage to be technically incorrect because a MOS as defined by [[Erv Wilson]] was to have ''exactly'' two specific intervals for each class other than multiples of the octave. When Wilson discovered MOS scales and found numerous examples, DE scales with period a fraction of an octave such as [[pajara]], [[augmented]], [[diminished]], etc. were not among them.
== Technical definition ==
 
== Extended definition ==
Let ''r'' ≥ 2 and let <math>S: \mathbb{Z}\to\mathbb{R}</math> be an ''r''-ary [[periodic scale]] with length ''n'' (i.e. ''S''(''kn'') = ''kP'' where ''P'' is the period), with step sizes ''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub>, i.e. such that <math>\Delta S(i) := S(i+1)-S(i)\in \{x_1, ..., x_r\} \forall i \in \mathbb{Z}.</math> The scale ''S'' is ''distributionally even'' if for every ''i'' ∈ {1, ..., ''r''},  (Δ''S'')<sup>&minus;1</sup>(''x''<sub>''i''</sub>) mod ''n'' is a [[maximally even]] subset of <math>\mathbb{Z}/n.</math> (For the original definition of DE, simply set ''r'' = 2.)
Let ''r'' ≥ 2 and let <math>S: \mathbb{Z}\to\mathbb{R}</math> be an ''r''-ary [[periodic scale]] with length ''n'' (i.e. ''S''(''kn'') = ''kP'' where ''P'' is the period), with step sizes ''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub>, i.e. such that <math>\Delta S(i) := S(i+1)-S(i)\in \{x_1, ..., x_r\} \forall i \in \mathbb{Z}.</math> The scale ''S'' is ''distributionally even'' if for every ''i'' ∈ {1, ..., ''r''},  (Δ''S'')<sup>&minus;1</sup>(''x''<sub>''i''</sub>) mod ''n'' is a [[maximally even]] subset of <math>\mathbb{Z}/n.</math> (For the original definition of DE, simply set ''r'' = 2.)


Using this definition, a scale word on ''r'' letters ''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub> is DE if and only if for every ''i'' ∈ {1, ..., ''r''}, the binary scale obtained by equating all step sizes except ''x''<sub>''i''</sub> is DE. This generalization of DE is thus an extraordinarily strong property: distributionally even scales over ''r'' letters are a subset of [[product word]]s of ''r'' &minus; 1 MOS scales, which can be thought of as temperament-agnostic [[Fokker block]]s.
Distributionally even scales over ''r'' letters are a subset of [[product word]]s of ''r'' &minus; 1 MOS scales, which can be thought of as temperament-agnostic [[Fokker block]]s. All DE scales in this extended sense are also [[billiard scales]].<ref>Sano, S., Miyoshi, N., & Kataoka, R. (2004). m-Balanced words: A generalization of balanced words. Theoretical computer science, 314(1-2), 97-120.</ref>
 
All DE scales in this extended sense are also [[billiard scales]].<ref>Sano, S., Miyoshi, N., & Kataoka, R. (2004). m-Balanced words: A generalization of balanced words. Theoretical computer science, 314(1-2), 97-120.</ref>


== List of distributionally even circular words ==
== List of distributionally even circular words ==

Revision as of 00:54, 5 May 2025

Not to be confused with Maximal evenness.

A scale is distributionally even if equating all step sizes except one will always result in a MOS. MOSses are the only distributionally even binary scales. The term was originally defined as a generalization of maximal evenness specifically for binary scales; this is the most convenient generalization.

Technical definition

Let r ≥ 2 and let [math]\displaystyle{ S: \mathbb{Z}\to\mathbb{R} }[/math] be an r-ary periodic scale with length n (i.e. S(kn) = kP where P is the period), with step sizes x1, ..., xr, i.e. such that [math]\displaystyle{ \Delta S(i) := S(i+1)-S(i)\in \{x_1, ..., x_r\} \forall i \in \mathbb{Z}. }[/math] The scale S is distributionally even if for every i ∈ {1, ..., r}, (ΔS)−1(xi) mod n is a maximally even subset of [math]\displaystyle{ \mathbb{Z}/n. }[/math] (For the original definition of DE, simply set r = 2.)

Distributionally even scales over r letters are a subset of product words of r − 1 MOS scales, which can be thought of as temperament-agnostic Fokker blocks. All DE scales in this extended sense are also billiard scales.[1]

List of distributionally even circular words

Below is the complete list of distributionally even circular words up to 10 letters, up to equivalence under reassignment of letters.

1 Letter

1 letter, unary: 0

2 Letters

2 letters, unary: 00

2 letters, binary: 01

3 Letters

3 letters, unary: 000

3 letters, binary: 001

3 letters, ternary: 012

4 Letters

4 letters, unary: 0000

4 letters, binary: 0001, 0101

4 letters, ternary: 0102

4 letters, quaternary: 0123

5 Letters

5 letters, unary: 00000

5 letters, binary: 00001, 00101

5 letters, ternary: 00102, 01012

5 letters, quaternary: 01023

5 letters, quinary: 01234

6 Letters

6 letters, unary: 000000

6 letters, binary: 000001, 001001, 010101

6 letters, ternary: 001002, 012012

6 letters, quaternary: 010203, 012013

6 letters, quinary: 012034

6 letters, 6-ary: 012345

7 Letters

7 letters, unary: 0000000

7 letters, binary: 0000001, 0001001, 0010101

7 letters, ternary: 0001002, 0010201, 0101012, 0102012

7 letters, quaternary: 0010203, 0102013, 0102032, 0120123

7 letters, quinary: 0102034, 0120134, 0120314

7 letters, 6-ary: 0120345

7 letters, 7-ary: 0123456

8 Letters

8 letters, unary: 00000000

8 letters, binary: 00000001, 00010001, 00100101, 01010101

8 letters, ternary: 00010002, 01020102, 01021012

8 letters, quaternary: 00100203, 01012013, 01020103, 01021013, 01230123

8 letters, quinary: 01020304, 01023042, 01230124

8 letters, 6-ary: 01023045, 01230145, 01230425

8 letters, 7-ary: 01230456

8 letters, 8-ary: 01234567

9 Letters

9 letters, unary: 000000000

9 letters, binary: 000000001, 000010001, 001001001, 001010101

9 letters, ternary: 000010002, 001020102, 010101012, 012012012

9 letters, quaternary: 001002003, 001020103, 001020302, 010201023, 010201032, 012031023

9 letters, quinary: 001020304, 010201034, 010201304, 010203042, 012013014, 012031024, 012301234

9 letters, 6-ary: 010203045, 012031045, 012301245, 012301425, 012301435, 012304135

9 letters, 7-ary: 012034056, 012301456, 012304156, 012304256

9 letters, 8-ary: 012304567

9 letters, 9-ary: 012345678

10 Letters

10 letters, unary: 0000000000

10 letters, binary: 0000000001, 0000100001, 0001001001, 0010100101, 0101010101

10 letters, ternary: 0000100002, 0010200102, 0101201012, 0102102012

10 letters, quaternary: 0001002003, 0010200103, 0010200302, 0101201013, 0102301023, 0120120123, 0120310213

10 letters, quinary: 0010200304, 0102103014, 0102301024, 0102301043, 0102304023, 0120130214, 0120310214, 0120310413, 0123401234

10 letters, 6-ary: 0102030405, 0102301045, 0102304025, 0102304053, 0120130145, 0120130415, 0120310415, 0120340253, 0123401235

10 letters, 7-ary: 0102304056, 0120340256, 0120340563, 0123401256, 0123401536

10 letters, 8-ary: 0120340567, 0123401567, 0123405267

10 letters, 9-ary: 0123405678

10 letters, 10-ary: 0123456789

Related topics

References

  1. Sano, S., Miyoshi, N., & Kataoka, R. (2004). m-Balanced words: A generalization of balanced words. Theoretical computer science, 314(1-2), 97-120.