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Re: Content MathML 3 in new working draft

From: Thomas E. Leathrum <leathrum@jsu.edu>
Date: Mon, 19 Nov 2007 12:53:52 -0600
Message-ID: <4741DBC0.4010302@jsu.edu>
To: m.kohlhase@jacobs-university.de
CC: www-math@w3.org

Michael Kohlhase wrote:
>> 1)  Will there be a precise decision procedure for deciding whether to
>> use "apply" or "bind"?  Do you use "bind" whenever there is a "bvar",
>> or is there a fixed set of operators (e.g. "int," "forall")  that will
>> require "bind"?  
>>     
> Here we have to distinguish "strict CMathML" vs "pragmatic CMathML". The
> former has a clear structure and a direct semantics on form of OpenMath
> Objects. The latter has a much freer structure, and covers (almost) all
> of what was legal in MathML2; its semantics is given in form of a
> translation to strict CMathML. In strict CMathML, <bvar> is  not allowed
> in an <apply>, and so <bind> has to be used. In pragmatic CMathML <bvar>
> in <apply> is allowed in some cases; the expressions in question
> correspond to <bind> expressions in strict CMathML.
>   
Yes, the question really is meant to apply to strict CMML3.  And OK, 
yes, I had gathered that  "bvar" would imply "bind".  So I guess my 
question really has to do with the converse:  are there going to be 
cases where you will have to use "bind" in the absence of a "bvar", 
because of the symbol role for the operator specified in the content 
dictionary?
>> The material about symbol roles specified in the content dictionaries
>> (Section 4.5.4) indicate that operators can take either the binder
>> role or the application role, but not both -- and yet, specifying no
>> role implies that the operator can be used either way.  
>>     
> We do not intend to have symbols without roles in the MathML Content
> Dictionaries, whether we generally want to make the role mandatory is
> still a matter of debate.
>   
>> Having a fixed set of operators that require "bind" seems problematic
>> to me, since some operators (e.g. "union") would seem to make sense
>> either way.  On the other hand, requiring "bind" whenever there is a
>> "bvar" would lead pretty quickly to some nonsensical code as well,
>> when a "bvar" is applied to an operator that doesn't support it -- if
>> the outer environment is still "apply," the "bvar" can be safely
>> ignored, but not so if using "bind."
>>     
> The union example you are referring to here is a (little documented)
> feature of MathML2, where we can use the <union/> symbol with two
> roles.  But MathML2 also divides the functionally analogous situation
> for addition and multiplication into distince symbols: <add/> and <sum/>
> (and <times/> and <prod/> respectively). In strict CMathML we have
> decided that we will always separate the operators into "small" and
> "big" operators (following TeX nomenclature). So there should not be
> much confusion.
>   
That will help, but that seems to be pointing in the direction of having 
a set of operators that require "bind" regardless of whether there is a 
"bvar" present.
>> 2) Will the "pragmatic" form of CMML3 ultimately be deprecated in
>> favor of the more verbose "canonical" form?  
>>     
> No, it will not. The two variants serve distinct and legitimate
> purposes. We consciously changed the names "canonical/legacy" to
> "strict/pragmatic" to make this clear. Strict CMathML is more suited for
> machine processing, whereas  Pragmatic CMathML is more geared towards
> human readability and authorability. So in your case, I indeed guess
> that pCMathML is more suitable.
>   
>> For my software, the "pragmatic" form would be the more realistic way
>> to handle the source syntax for the translator, but I could add some
>> code (or some sort of external association similar to the content
>> dictionaries) to make sure the output is "canonical."  
>>     
> Rather than restricting to strict CMathML as an output format I would
> probably add a switch that allows to generate the respective variant.
>   
Given that my translator uses a mostly syntactic method of going from 
its input source to CMML2 output, there is very little reference to 
particular identifiers, so the translator as it stands now should work 
for "pragmatic" CMML3.  So what I really need to work on is a translator 
configuration for "strict" CMML3.  In order to continue using ordinary 
identifiers rather than "csymbol" references to the content 
dictionaries, though, I will need to put together some sort of external 
association between the two, akin to the content dictionaries.
>> However, relevant to the first question, the pragmatic form uses
>> "apply" as in CMML2 in places where the canonical form would require
>> "bind," which for my purposes just muddies the waters even more.
>>     
> I personally do not think that this is a problem, but maybe you would
> care to elaborate.
>   
I suppose the problem would depend on whether there will be a clear 
distinction in the mark-up between when you are using "pragmatic" or 
"strict", the way there currently is for the distinction between 
"presentation" and "content" (they *can* be mixed, but only by enclosing 
the mixed code inside e.g. "semantics" tags).  If there is no such clear 
distinction, you could have a segment of "pragmatic" code with its 
"apply" tags inside a segment of "strict" code with its "bind" tags, and 
the difference specified by the symbols and their roles would become 
rather meaningless.


Regards,
Tom Leathrum
Received on Monday, 19 November 2007 18:54:35 GMT

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