[om] comments on documents
Richard Fateman
fateman at cs.berkeley.edu
Fri May 17 18:18:36 CEST 2002
David Carlisle wrote:
>> It seems from a casual reading, that
>>
>> OM encoding doesn't specify presentation.
>>
>
> true
>
>
>> MathML doesn't specify content.
>>
>
> false (as is pointed out in the comparison, MathML has a content part
> that directly corresponds to OpenMath constructs)
Well, the MathML content is optional and
never used in practice. It seems to be not specified very well,
though frankly I have not kept up with it. If the MathML
content definition is by reference to the OM encoding corresponding
to that MathML content, and is therefore equivalent to a
subset of OM, then the relationship should be made crystal clear.
That is, MathML content, if it is given,
is an abbreviation for a subset of OM. period.
>
>
>>Both of these are essentially false, easily observed by
>>(a) the conversion of OM to MathML and to TeX. So OM specifies
>>(or can be used to specify) presentation.
>>
>
> No. In that case the presentation is specified by the transform. You can
> have different transformations giving different presentations of the
> same OM object. The OM object itself does not prefer any of these
> formats. I can decide that I'm going to present every OM function
> application as a prefixed function call as f(x,y) (ie no infix
> operations) and write a transform to use that presentation mapping to
> TeX or MathML or any other presentation language. At other times I can
> use a different transformation that uses infix operators or lisp (f x y)
> syntax or any other presentation.
>
I do not see this as differing in any essential way from the possibility
that two browsers may decide to take a single MathML utterance and
display it in different ways, since one might transform it into
a narrow column display with multiple lines, and another might
use horizontal scrolling, and other might use AsTer to read it
out loud. Yes, you could make a case that
a
-----
b
and a/b
and a*b^(-1)
-1
ab
etc should be denoted by the same content e.g. in lisp (* a (expt b -1))
but that would imply a canonicalization of some sort. You don't
provide that, so in fact the OM content in most cases gives
a big fat hint as to what should be displayed, by choosing
to transmit only one of the (infinite) number of equivalent
objects.
>
>>(b) MathML has a content component, which could either
>>point to some OM piece or not.
>>
>
> Yes that is clearly stated with examples in the document that you are
> refering to so I'm not sure of your point here.
>
Just that if you stated that MathML is a subset of OM
you would not have to distinguish them.
>
>
>>One technique used in industry where
>>there are competing technologies is to stamp out
>>competition by attempting to elevate one proposal
>>to be the standard.
>>
>
> But since OM and MML are not competing this isn't particularly
> relevant.
Actually, this illustrates and emphasizes my point.
You don't even know what OM is competing with. I would
suggest the competition includes the existing and
very widespread "standardized" forms from
Mathematica
Maple
Macsyma
Reduce
Axiom
...
as well as communication protocols like the ones proposed
and implemented by
Bruce Char
Paul Wang
MINSE
TechExplorer
Scientific Word
Macintosh Graphing Calculator (for communicating
with TILU)
just to name a few.
Several of these systems distinguish between content
and some external forms (boxes, math standards, TeX...)
>
>
>>To what established international body is the OM
>>standard going to be submitted?
>>
>
> It may be submitted to some external body but there are no immediate
> plans to do so. It's not clear it would serve any immediate purpose.
It would provide a review outside the OM club.
> There's no sign that a change of status would encourage anyone to use OM
> who is currently not using it, or vice versa.
It would mean that you could use the word "standard"
with the same technical connotation as
"ANSI Standard" C, Common Lisp, ... or
"IEEE Standard" binary floating point arithmetic ...
RJF
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