Permutation product set: Difference between revisions
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A '''permutation product set''' (PPS) is obtained from a chord C = {1,''a''_1,''a''_2,...,''a''_''n''} as follows: | A '''permutation product set''' (PPS) is obtained from a [[chord]] C = {1,''a''_1,''a''_2,...,''a''_''n''} as follows: | ||
Let ''b''_1,...,''b_''''n'' be the | Let ''b''_1,...,''b_''''n'' be the [[interval]]s between successive [[note]]s of the chord: ''b_i'' = ''a_i''''/a_''(''i''-1). These ''n'' intervals can be permuted in ''n''! ways, yielding ''n''! different chords: | ||
{1,''b''_s(1),''b''_s(1)*''b''_s(2),...} where s is a permutation of {1,2,...,''n''} | {1,''b''_s(1),''b''_s(1)*''b''_s(2),...} where s is a permutation of {1,2,...,''n''} | ||
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The union of these ''n'' chords is the PPS of C. PPSes may or may not be octave equivalent. | The union of these ''n'' chords is the PPS of C. PPSes may or may not be octave equivalent. | ||
Permutation product sets were introduced by Marcel De Velde in 2009 to explain the diatonic scale. | Permutation product sets were introduced by [[Marcel De Velde]] in 2009 to explain the [[diatonic scale]]. | ||
==Special cases== | ==Special cases== | ||
If C is a harmonic series, {1/1,2/1,...,''n''/1}, then the PPS of C is called the ''n''-limit harmonic permutation product set (HPPS). ''n'' can be even. | If C is a [[harmonic series]], {1/1,2/1,...,''n''/1}, then the PPS of C is called the ''n''-[[limit]] harmonic permutation product set (HPPS). ''n'' can be even. | ||
The octave equivalent 6-limit HPPS is the union of the major and minor diatonic scales: | The [[Octave equivalence|octave equivalent]] 6-limit HPPS is the union of the major and minor diatonic scales: | ||
1/1 9/8 6/5 5/4 4/3 3/2 8/5 5/3 9/5 15/8 2/1 | 1/1 9/8 6/5 5/4 4/3 3/2 8/5 5/3 9/5 15/8 2/1 |