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Re: asn06 take 2 (Abstract Syntax as a kind of ontology?)

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Tue, 21 Nov 2006 15:57:51 +0000
Message-ID: <456321FF.40502@hplb.hpl.hp.com>
To: Christian de Sainte Marie <csma@ilog.fr>
CC: Sandro Hawke <sandro@w3.org>, public-rif-wg@w3.org

Christian de Sainte Marie wrote:
> 
> Dave Reynolds wrote:
> 
>>
>> Sandro Hawke wrote:
>>
>>> Thinking more about the abstract syntax question, I find myself
>>> wondering how an abstract syntax is really different from an ontology.
>>> Is there any practical difference between an ontology of Horn rules and
>>> an abstract syntax for Horn rules?  
>>
>>
>> One possible difference is that in an abstract syntax you can say 
>> whether ordering is significant or not.  Sure, as you argue, one 
>> benefit is that you can say "ordering is not significant here" but you 
>> can also (at least in ASN.1) say "ordering *is* significant here". Or 
>> perhaps that is just a feature of ASN.1 rather than of abstract syntax 
>> notations in general.
>>
>> However, I think an ontology is closer to want we actually want for 
>> RIF and the only places we need to preserve order (e.g. in 
>> function/relation arguments) can be handled in an ontology.
> 
> What I read, here (and that was already my impression before), is that 
> UML would be even better than OWL (except for not being a W3C standard, 
> of course :-)
> 
> What are the drawbacks of UML (apart from the ones we already discussed: 
> interchange within the WG, but that is just a question of agreeing on a 
> format; and not everybody being familiar, but that is true of OWL too, 
> isn't it?)? A plus for UML could be that implementors might be more 
> likely to know it.

I agree UML is genuine option.

As you say there is the "interchange within the WG" issue that we've 
already discussed [1].

Second there is the issue that the point of this is for extensibility. 
In Sandro's "use a small OWL fragment with syntactic sugar" proposal we 
can exploit the extensibility of OWL. When an extension needs to add new 
productions to an existing abstract syntax node it just declares a new 
subclass. That new declaration can be in another self contained OWL 
model and merging the two models is both well defined and simple. It's 
not clear to me that either is true of merging in the UML case, but 
perhaps that's a limitation of my knowledge of UML.

Third, in Sandro's extensibility proposal [2] a RIF processor would go 
out and resolve the namespace of a unknown syntax element and obtain ... 
something. With the asn06-as-OWL approach that something could be or 
include OWL. Whereas the equivalent for UML, XMI, really seems to be a 
tool for diagram exchange rather than runtime data exchange [3].
Of course, we might not want to do this anyway but it'd be nice to keep 
the option open at this stage.

[By the way, how does "list of X" work in UML?]

Dave

[1] My personal experience of UML tool interchange has been bad but it's 
true that one could stick to a single tool.

[2] http://lists.w3.org/Archives/Public/public-rif-wg/2006Nov/0031.html

[3] XMI was at the heart of my bad experiences noted in [1], it may well 
be that XMI is suitable for runtime exchange and is well supported these 
days and my concerns are obsolete.
Received on Tuesday, 21 November 2006 15:58:14 GMT

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