Re: Semantic Web User Agent Conformance

A few quick thoughts:

1) Is asking the number of triples an interesting question. Why?
2) In the case of an OWL document, I would be interested in the  
entailments, not the number of base triples. OWL models, can, in  
general, be infinite, even given a finite description.
3) Should this sort of activity not first be driven by defining some  
example set of activities for semantic web agents? From these  
activities we could get requirements, and then, having a number of  
them, perhaps generalize

Examples of activities might be
- Browsing and creating tables using tabulator
- Aggregating for the purposes of doing certain kinds of queries (the  
kind of query matters)
- Indexing so that people can find documents
etc

-Alan

On Nov 22, 2007, at 11:46 AM, Sean B. Palmer wrote:

>
> One of the biggest Semantic Web questions people are asking right now
> is: when a Semantic Web User Agent gets a document, how many normative
> ways of getting triples from it are there? Or, from the other
> direction: how many triples is the author asserting in some document?
> The answer is, generally, "how long is a piece of string?", but in
> fact there are lots of cases in which we need to construct more
> specific answers.
>
> I'm proposing some kind of work on conformance levels for Semantic Web
> User Agents, such that when someone says "how many triples are in
> $uri", we can answer confidently "a Class 2 Semantic Web User Agent
> will return 53 triples"; or perhaps not *that* abstract, but along
> those lines. It would be nice for example if we could specify things
> very granularly too, so a vocabulary for specifying user agent
> conformances on levels from the granular (single test cases) to the
> abstract ("I support RDF/XML") would also be good.
>
> The aim is for document producers to know how many UAs out there
> support the format that they're using, and to give some kind of
> regularity to what is currently a bundle of ad hoc solutions.
>
> As a bit of context, here are some people who've been thinking about
> this specifically from an engineering point of view:
>
> http://chatlogs.planetrdf.com/swig/2007-11-22.html#T15-55-12
> - Chimezie Ogbuji
>
> http://www.w3.org/DesignIssues/diagrams/arch/follow
> - Tim Berners-Lee
>
> http://swhack.com/logs/2007-11-22#T13-09-31
> - Keith Alexander
>
> http://swig.xmlhack.com/2007/11/22/2007-11-22.html#1195725171.081142
> - me
>
> There's also been a lot of discussion about Xiaoshu Wang's paper on
> kinda the same issues, but I think that's a distraction so I won't
> bother to link to it.
>
> Now the case that got me thinking about this today is RDFa. The
> current RDFa specification states as follows:
>
> "A conforming RDFa Processor MUST make available to a consuming
> application a single RDF [graph] containing all possible triples
> generated by using the rules in the Processing Model section."
> - http://www.w3.org/TR/rdfa-syntax/#uaconf
>
> What a huge tax on Semantic Web User Agents that also have to be
> conforming GRDDL agents and conforming RDF/XML agents and so on! GRDDL
> in particular is a tricky case because the conformance is left open
> but it recommends that you implement *all* of the underlying
> processing mechanisms and then XSLT 1.0 as the main transformation
> language; but this particular conformance class doesn't have a name,
> it's just represented in the GRDDL Test Cases REC.
>
> I've already filed a comment about RDFa, and I've asked for
> @profile=".../rdfa" to be a SHOULD in RDFa documents, and to absolve
> conforming user agents of the responsibility to parse anything other
> than an @profile using RDFa document. There are some important
> comments in that thread that I've made, e.g.:
>
> [[[
> The burden is where you have a URI, and you know it gives triples, but
> you can't be sure that the author isn't going to use eRDF one day,
> change their mind and use some GRDDL hDialect the next, and then RDFa
> the next. So you have to try *all* of the available mechanisms to be
> safe.
>
> Now, if there were some well defined heuristics for telling which
> possible transformations might apply, that would greatly reduce the
> burden on the suite of parsers required to handle all this.
> ]]] - Re: RDFa RFE: No Mandated DOCTYPE
> http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007Nov/ 
> 0065
>
> After that, I considered (and still consider) that this work is
> probably in the remit of the SW Deployment WG, and wrote to them about
> it:
>
> [[[
> If you really want to take this to its logical conclusion, it would be
> nice to have a vocabulary for describing the capabilities of Semantic
> Web user agents to consume various documents, a writeup of the
> heuristics that they ought to use, and a kind of extra layer of
> conformance levels for Semantic Web user agent authors to try to meet.
> "Don't wanna support all of GRDDL? Here are a few common subsets that
> are well deployed."
>
> This should be based on some level of description, looking to see what
> kinds of documents people are actually using, and prescription, what
> kinds would be good to produce especially in future when things like
> RDFa go to rec.
> ]]] - Best Practices Issue: RDF Format Discovery
> http://lists.w3.org/Archives/Public/public-swd-wg/2007Nov/0056
>
> I think that this would be valuable work to carry out. The SWD WG
> haven't replied yet, but I was wondering what the Semantic Web
> Interest Group thought, and I thought that at the very least I ought
> to keep people over here informed.
>
> Thanks,
>
> -- 
> Sean B. Palmer, http://inamidst.com/sbp/
>

Received on Thursday, 22 November 2007 17:52:45 UTC