[Om] Multistep "equation" symbol?

Professor James Davenport jhd at cs.bath.ac.uk
Tue May 12 14:08:05 CEST 2009

On Tue, May 12, 2009 11:19 am, Christoph LANGE wrote:
> Hi Peter,
> 2009-05-12 10:58 Peter Horn <hornp at mathematik.uni-kassel.de>:
>> From
>> http://www.openmath.org/standard/om20-2004-06-30/openmath2.rng
>> I understand that OMFOREIGN must contain valid XML. You frequently use
>> stuff like:
>> > <OMA><OMS name="multistep">
>> >   <OMFOREIGN encoding="LaTeX">
>> >     \sqrt{n^2+1} - n
>> >   </OMFOREIGN>
>> which is -- from my point of view -- not valid OpenMath at all.
> Where is the problem?  OMFOREIGN need not contain OpenMath objects, but,
> as
> you said above, valid XML (of datatype string, as specified in the Relax
> NG
> schema).  "\sqrt{n^2+1} - n" is a valid string in XML.  I cannot give any
> recommendation on how your parser should treat OMFOREIGN, but it is likely
> that they will encounter encodings (such as LaTeX) that they don't
> understand -- because they are, well, _foreign_.
The normal recommendation is to ignore all those for which one does not
understand, and WANT to understand (for example, your system might
understand LaTeX, but not be in type-setting mode at that instant) the
"encoding". In theory OpenMath ought to set up an RFC-like register of
such encodings, but that's not the most urgent thing on our agenda.

James Davenport
Visiting Full Professor, University of Waterloo
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

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