W3C home > Mailing lists > Public > public-rdf-in-xhtml-tf@w3.org > July 2007

Re: Determination of subjects/objects (was: ISSUE-42)

From: Knud Hinnerk Möller <knud.moeller@deri.org>
Date: Mon, 30 Jul 2007 19:57:47 +0100
To: Mark Birbeck <mark.birbeck@formsPlayer.com>
Cc: Dan Brickley <danbri@danbri.org>, Manu Sporny <msporny@digitalbazaar.com>, public-rdf-in-xhtml-tf@w3.org
Message-id: <31F3086E-EDD3-4621-A90B-B51ACEBA4288@deri.org>
Ok, here is my use case, if I remember correctly:

- I generate RDFa (using the SWRC ontology) from BibTeX
- a paper has multiple authors
- there are many ways to represent that in RDF
- SWRC just uses multiple (book swrc:author aFOAFPerson) statements  
for that
- however, that doesn't keep the order of the authors
- that's why I _also_ use one (book swrc_ext:authorList  
sequenceOfAuthors) statement
- I do both because I want to stay compatible to the original SWRC,  
but also give the possibility of getting the author order
- of course the foaf:Person resources in both approaches should be  
the same
- I don't have URIs for the authors, so I need to use bnodes (or make  
up URIs, which I don't want to do)
- because I want to refer to the same resource through both  
swrc:author and swrc_ext:authorList, I need to be able to name the  
bnodes within that graph
- i.e., I need named bnodes

I hope that makes sense. :)


Am 30.07.2007 um 18:18 schrieb Mark Birbeck:

> Hi Dan/Knud,
> The issue isn't bnodes, since we do have those in RDFa. The question
> is whether to support 'named bnodes', which you get in RDF by using
> @nodeID. (Early drafts of RDFa actually used to have a nodeID
> attribute.)
> I'm really interested to hear comments on the use-cases for this,
> which will most likely come from those who use RDF a lot. The main
> argument for its use in RDF more generally is to be able to have a
> bnode that can be referenced from within a graph, but that cannot be
> referenced outside that graph. In RDFa terms that would mean that you
> have created a bnode that you want to be able to refer to in some
> other part of the document, but you *don't* want anyone else in the
> world to be able to make statements about it.
> I can't think of any situations where I'd use that myself, but that
> doesn't mean a thing. :)
> Regards,
> Mark
> On 30/07/07, Dan Brickley <danbri@danbri.org> wrote:
>> Knud Hinnerk Möller wrote:
>>> Hi,
>>> Am 30.07.2007 um 17:15 schrieb Manu Sporny:
>>>> Mark Birbeck wrote:
>>>>> I haven't had a chance to re-read this thread, so I'm not going  
>>>>> to say
>>>>> anything on the substance. But if you don't mind, I'd like to  
>>>>> comment
>>>>> on a recurring theme, which seems exemplified by the following:
>>>>>> I have a visceral problem with about="_:", and that is that it  
>>>>>> makes
>>>>>> bnodes explicit, which I really don't want to do to HTML  
>>>>>> authors. That's
>>>>>> just too much RDF.
>>>>> I don't see the need to 'protect' authors who are not familiar  
>>>>> with
>>>>> RDF from RDF constructs that they will never use. If someone  
>>>>> from the
>>>>> RDF community thinks this is useful, and _if_ we can support it
>>>>> without it getting in the way, then why not?
>>>> Constructs such as "_:" are scary to non-RDF folks. :) From a
>>>> historically RDF-unaware perspective (mine), I stared at the "_:"
>>>> construct and had no idea what it does. It is not very intuitive.
>>>> Even having seen it, I haven't taken the time to look up what it  
>>>> means.
>>>> It will probably make sense when I do, but to somebody that is not
>>>> trained in CS/EE/ECE/etc., this is a scary construct. To the lay  
>>>> web
>>>> page author, it is syntactic gibberish.
>>>> There is already a very strong feeling in the Microformats  
>>>> community
>>>> that RDFa is far too complicated for most web page authors. The  
>>>> last
>>>> thing most of them want to learn is yet another language syntax for
>>>> describing what they see as "corner-cases of the language".
>>>> I see your argument: If they aren't going to use it, and if it  
>>>> doesn't
>>>> cause any harm, then why not put it in there?
>>>> I would argue that you shouldn't put things in there that aren't
>>>> absolutely necessary. It complicates the RDFa specification. If  
>>>> there is
>>>> a need in the future, you can always add it in a later revision.
>>> I would really argue to have bnodes in RDFa: I know they are very
>>> unpopular, and vocabularies like FOAF now recommend against using  
>>> them.
>> No they don't :) well, foaf in particular...
>> I put a #me into the FOAF spec example, that's all.
>> RDF is a language for representing and aggregating partial  
>> information
>> into a greater whole. Sometimes that information lacks statements,
>> sometimes those statements are missing well known identifiers.  
>> Sometimes
>> the things the statements are about don't even have well known  
>> identifiers.
>> There are things in FOAF such as isPrimaryTopicOf which are  
>> designed to
>> help people live in such a world. But there is nothing FOAF or  
>> other RDF
>> vocabs can do to get away from the basic fact: informational is not
>> universally and evenly available. RDF authors do not have a godlike
>> access to every fact and every identifier they might need. And so RDF
>> data is inevitably a lossy, gappy thing. Sometimes missing  
>> statements,
>> sometimes missing URIs. Because RDF is written by people, and  
>> people do
>> not know everything. If they did, why would they bother exchanging  
>> RDF
>> files with each other? :) And so we have bnodes.
>> That said, "_:" in RDFa worries me too.
>> Dan
> -- 
>   Mark Birbeck, formsPlayer
>   mark.birbeck@formsPlayer.com | +44 (0) 20 7689 9232
>   http://www.formsPlayer.com | http://internet-apps.blogspot.com

>   standards. innovation.

Knud Möller, MA
+353 - 91 - 495086
Smile Group: http://smile.deri.ie

Digital Enterprise Research Institute
   National University of Ireland, Galway
Institiúid Taighde na Fiontraíochta Digití
   Ollscoil na hÉireann, Gaillimh

Received on Monday, 30 July 2007 18:59:48 UTC

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