[Om] invisible times and invisible plus

[Professor James Davenport]

On Mon, August 31, 2009 8:39 pm, Christoph LANGE wrote:
> 2009-08-31 17:06 Professor James Davenport <jhd at cs.bath.ac.uk>:
>> I suspect we want to be able to write
>> <OMATTR>
>>   <OMATP>
>>     <OMS cd="presentation_hacks" name="use_symbol"/>
>>     <OMFOREIGN encoding="MathML-Presentation">
>>       <math xmlns="http://www.w3.org/1998/Math/MathML">
>>         <mo>&InvisiblePlus;</mo>
>>       </math>
>>     </OMFOREIGN>
>>   </OMPATP>
>>   <OMS name="plus" cd="arith1"/>
>> </OMATTR>
>>
>> or some such.
>
> Indeed, good point.  I think that would almost work out of the box with
> the existing implementations of renderers.
That would be truly wonderful. It would solve the 'my group operation is
called' problem quite neatly.
> However, it may easily become more intricate.  Suppose the default way of
> rendering division (according to some *.ntn notation dictionary) is a/b
> instead of
I'm probably being dense here, but I don't see what the default rendering
of division has to do with the issue.
Unless, of course, we assume our rendered comes across mixed_fraction,
doesn't understand it, applies the FMP, and then tries to render the
result.
>  a
> ---
>  b
>
> then the approach above would no longer work.  Instead we'd have to
> attribute
> the complete (plus a (divide b c)) expression with, well, maybe some
But there wouldn't be (plus a (divide b c)) fragment unless the FMP had
been applied.
> Presentation MathML fragment with placeholders that would then be replaced
> by the renderings of the respective arguments.  Something similar to the
> patterns in those pattern-matching-based notations.

James Davenport
Recently: Visiting Full Professor, University of Waterloo
Now back as:
Acting Head of Department, Computer Science,
Hebron & Medlock Professor of Information Technology and
Chairman, Powerful Computing WP, University of Bath
OpenMath Content Dictionary Editor and Programme Chair, OpenMath 2009
IMU Committee on Electronic Information and Communication