Generator-offset property: Difference between revisions

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Inthar (talk | contribs)
Theorems: GO property now includes well formed wer the generator
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* is generator-offset (chain lengths off by 1)  
* is generator-offset (chain lengths off by 1)  
* has odd length ''n''
* has odd length ''n''
* the generator is subtended constantly.


Then the scale is SGA.
Then the scale is SGA.


Note: The third condition is required. Without it, this is false for the 5-note scale 0 250 300 700 750 1200 with alternants 700 and 50: the 1-steps form the chain 250 50 400 50 450 and the 2-steps form the chain 300 450 700 250 500.
==== Proof ====
==== Proof ====
Assume that the generator is a ''k''-step and ''k'' is even. (If ''k'' is not even, invert the generator.) On some tonic p we have a chain of ceil(''n''/2) notes and on some other note ''p' = p'' + offset (not on the first chain) we'll have floor(''n''/2) notes.
Assume that the generator is a ''k''-step and ''k'' is even. (If ''k'' is not even, invert the generator.) On some tonic p we have a chain of ceil(''n''/2) notes and on some other note ''p' = p'' + offset (not on the first chain) we'll have floor(''n''/2) notes.