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## Re: Lilypond's internal pitch representation and microtonal notation

 From: Joseph Wakeling Subject: Re: Lilypond's internal pitch representation and microtonal notation Date: Tue, 21 Sep 2010 16:05:52 +0200 User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100915 Lightning/1.0b1 Thunderbird/3.0.8

```On 09/21/2010 02:16 PM, Hans Aberg wrote:
> Yes - accidentals do not affect the degree: they are of degree zero. One
> can add notes and intervals on this abstract level, and the degrees add
> as well. In mathematics, a function f is called a homomorphism (of
> abelian groups) when f(0) = 0, f(x + y) = f(x) + f(y), f(-x) = -f(x).
> The degree, which is the sum of the coefficients is a homomorphism.

Ahhh, NOW you are bringing the discussion into terms that I can
appreciate.  I have studied group theory, but it was 10+ years ago
without using it since, and hence my recollection is extremely flaky.
So it was difficult to work out what you were getting at with your
earlier explanations which tried to limit the use of precise
mathematical terminology.  In my case I need _more_ maths, not less,
because it helps me re-familiarize myself with the exact concepts I need
to understand your system ... :-)

Anyway, I will take the time to go over your answers properly and surely
be back with more questions.

>> ... so if we extend this vectorial representation to a 3D case for
>> quarter-tones, (x_M, x_m, x_q), (NB my q is different from yours:-)
>
> Yes, some mathematicians do that error, too, though in print, q as a
> variable might be typeset in italic, whereas as constant in upright type.

I don't understand what you consider an error here.  I understood very
well that you were using the letter q to represent a coefficient.  I
just wanted to use q to represent a group element, so re-labelled the
coefficients of the elements M, m and q by x_M, x_m and x_q.

It may be an error to think of "vectorial representation", but ... :-P

```

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