[om] comments on documents

Paul Libbrecht paul at activemath.org
Sat May 18 00:34:46 CEST 2002

On Friday, May 17, 2002, at 11:23 PM, Richard Fateman wrote:
> Consider this expression in Maple syntax:
> 	exp(x)*exp(-y)+exp(x-y)+exp(x)/exp(y);
> If there is a natural encoding in OM then this should come out
> as  foo + foo + foo    and then there would be no way for a
> presentation-only program to translate this back into  the equivalent 
> of the Maple expression.

But who ever dared say that someone wanted to make a predictable 
presentation to OpenMath translator ?
I hope no-one because, as you state, it's impossible and simply out of 
(the one of MathType is recognized to be a dead-end)

>   My conclusion is that the OM content must give essential
> hints on how to display the expression.  I suppose one could
> put presentation tags on each of the 3 items within the semantics,
> but would your XSL translator be ready for that?

That's the major point of using OpenMath instead of any presentational 
formula markup: you separate presentation information from the content !

>> In the XSL stylesheets I have for going to presentation there are some
>> fairly ad hoc rules about when to use a visible and when to use an
>> invisible times, which you get depends on the values of a and b, not on
>> the operator used for multiplication.
> Your heuristics might not be the same as mine or those in documents
> I have been manipulating which use both  invisible space and \cdot
> for multiplication, but with different precedence.

Presentation info is to be so much separate that, precisely, it will 
honour your style of writing, e.g., a function composition which is 
different than in the classical old english school.
This preference is encoded in a presentation mechanism (like an XSL 
stylesheet) but the content saying this is a function application is 
still there in the back and maybe even can be seen in some (hidden) way 
in the presentation.

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