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Re: Subjects as Literals, [was Re: The Ordered List Ontology]

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Thu, 01 Jul 2010 10:42:11 -0400
Message-ID: <4C2CA943.8090302@openlinksw.com>
To: Pat Hayes <phayes@ihmc.us>
CC: Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
Pat Hayes wrote:
>
> On Jun 30, 2010, at 3:49 PM, Kingsley Idehen wrote:
>
>> Pat Hayes wrote:
>>>
>>> On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
>>>
>>>> Nathan wrote:
>>>>> Pat Hayes wrote:
>>>>>> On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
>>>>>>> On Wed, 30 Jun 2010 10:54:20 +0100
>>>>>>> Dan Brickley <danbri@danbri.org> wrote:
>>>>>>>> That said, i'm sure sameAs and differentIndividual (or however 
>>>>>>>> it is
>>>>>>>> called) claims could probably make a mess, if added or removed...
>>>>>>>
>>>>>>> You can create some pretty awesome messes even without OWL:
>>>>>>>
>>>>>>>   # An rdf:List that loops around...
>>>>>>>
>>>>>>>   <#mylist> a rdf:List ;
>>>>>>>       rdf:first <#Alice> ;
>>>>>>>       rdf:next <#mylist> .
>>>>>>>
>>>>>>>   # A looping, branching mess...
>>>>>>>
>>>>>>>   <#anotherlist> a rdf:List ;
>>>>>>>       rdf:first <#anotherlist> ;
>>>>>>>       rdf:next <#anotherlist> .
>>>>>>>
>>>>>>
>>>>>> They might be messy, but they are *possible* structures using 
>>>>>> pointers, which is what the RDF vocabulary describes.  Its just 
>>>>>> about impossible to guarantee that messes can't happen when all 
>>>>>> you are doing is describing structures in an open-world setting. 
>>>>>> But I think the cure is to stop thinking that possible-messes are 
>>>>>> a problem to be solved. So, there is dung in the road. Walk round 
>>>>>> it.
>>>>>>
>>>>>
>>>>> Could we also apply that to the 'subjects as literals' general 
>>>>> discussion that's going on then?
>>>>>
>>>>> For example I've heard people saying that it encourages bad 
>>>>> 'linked data' practise by using examples like { 'London' a x:Place 
>>>>> } - whereas I'd immediately counter with { x:London a 'Place' }.
>>>>>
>>>>> Surely all of the subjects as literals arguments can be countered 
>>>>> with 'walk round it', and further good practise could be aided by 
>>>>> a few simple notes on best practise for linked data etc.
>>>>
>>>> IMHO an emphatic NO.
>>>>
>>>> RDF is about constructing structured descriptions where "Subjects" 
>>>> have Identifiers in the form of Name References (which may or many 
>>>> resolve to Structured Representations of Referents carried or borne 
>>>> by Descriptor Docs/Resources). An "Identifier" != Literal.
>>>
>>> What ARE you talking about? You sound like someone reciting doctrine.
>>>
>>> Literals in RDF are just as much 'identifiers' or 'names' as URIs 
>>> are. They identify their value, most clearly and emphatically. They 
>>> denote in exactly the same way that URIs denote. "23"^^xsd:number   
>>> is about as good an identification of the number twenty-three as you 
>>> are ever likely to get in any notational system since ancient 
>>> Babylonia.
>>
>> Yes, but ancient Bablyonia != World Wide Web of Structured Linked 
>> Data, slightly different mediums with some shared characteristics :-)
>>
>> The World Wide Web is becoming a Distributed DBMS (in my eyes). Thus, 
>> unambiguous naming matters.
>
> A topic for a longer discussion; but irrelevant here, since typed 
> literals are as unambiguous as a name can possibly get.
>
>>
>> Literal Subjects aren't a "show stopper" per se. (esp. for local RDF 
>> data). My gripe simply boils down to the nuisance factor introduced 
>> by data object name ambiguity in a distributed data object oriented 
>> realm such as the emerging Web of Linked Data.
>>
>> What does ""23"^^xsd:number " mean to anyone in a global data space?
>
> It means the number twenty-three, everywhere and for all time, because 
> this meaning can be computed from the very syntactic form of the name. 
> How unambiguous can something get?

Pat,

Re. RDF's triples, What is a Subject? What is an Object?.

If they are the same thing, why on earth do we use Names (with 
implications) to describe the slots in an RDF triple?

I've only once seen the RDF triple referred to as O-R-O (by @danbri) 
i.e., Object-Relation-Object.

In addition, I don't see Information and Data as being the same thing. 
Information (as I know it) is about Data + Context.  Raw Data (as I know 
it) is about: a unit of observation and deemed worthy of description by 
its observer.  You have to give Names to subject of a description. 
"23"^^xsd:number  isn't a Name.

**
I guess my own subtle mistake (re. this thread) is deeming Identifiers 
and Names to be equivalent , when they aren't :-) Of course, one can use 
an Identifier as a Name, but that doesn't make them equivalent.
**


One clear point of divergence here is that I am focused on the Web as 
Dist. DBMS that leverages 3-tuples + HTTP URIs in the S, P, and 
optionally O slot (aka. HTTP based Linked Data).

To conclude:

Name != Identifier.

I believe Subject == Name (an Identifier based Name) re. RDF triples 
otherwise the triple should be described as: O-R-O or O-P-O.

I believe an S-P-O triple is a piece of information (Data Object has a 
Name and at least one Attribute=Value pair).

What I desscribe actually has zilch to do with RDF as I am inclined to 
believe you see RDF :-) Thus, in a way, the literal-subject debate may 
simply help everyone understand and accept that RDF != Linked Data. 
Thus, providing additional proof that RDF isn't mandatory or even 
required re. delivery of  HTTP based Linked Data.

RDF based Linked Data != RDF. They are different things, clearly.  We 
can't have it both ways (** Pat: not for you, that's for those that deem 
RDF and Linked Data inextricably linked **).


BTW - I still have no idea if RDF and RDF/XML are really distinct. HTML 
and N3 built the Web of Linked Data, but N3  remains a 2nd or 3rd class 
citizen whenever we talk about the pragmatic aspects of what continues 
to be inappropriately labeled as an RDF virtue i.e. Linked Data.

Danbri:

I agree with the essence of your earlier post!


Kingsley


>
> Pat
>
>
>> I know the meaning of: 
>> <http://km.aifb.kit.edu/projects/numbers/web/n23#this>, based on the 
>> resource I deref at: <http://km.aifb.kit.edu/projects/numbers/web/n23>
>>
>>
>>
>> Kingsley
>>
>>
>>>
>>> Pat Hayes
>>>
>>>>
>>>> If you are in a situation where you can't or don't want to mint an 
>>>> HTTP based Name, simply use a URN, it does the job.
>>>>
>>>>
>>>>>
>>>>> Best,
>>>>>
>>>>> Nathan
>>>>>
>>>>>
>>>>
>>>>
>>>> -- 
>>>>
>>>> Regards,
>>>>
>>>> Kingsley Idehen          President & CEO OpenLink Software     Web: 
>>>> http://www.openlinksw.com
>>>> Weblog: http://www.openlinksw.com/blog/~kidehen
>>>> Twitter/Identi.ca: kidehen
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>> ------------------------------------------------------------
>>> IHMC                                     (850)434 8903 or (650)494 3973
>>> 40 South Alcaniz St.           (850)202 4416   office
>>> Pensacola                            (850)202 4440   fax
>>> FL 32502                              (850)291 0667   mobile
>>> phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>> -- 
>>
>> Regards,
>>
>> Kingsley Idehen          President & CEO OpenLink Software     Web: 
>> http://www.openlinksw.com
>> Weblog: http://www.openlinksw.com/blog/~kidehen
>> Twitter/Identi.ca: kidehen
>>
>>
>>
>>
>>
>>
>
> ------------------------------------------------------------
> IHMC                                     (850)434 8903 or (650)494 3973
> 40 South Alcaniz St.           (850)202 4416   office
> Pensacola                            (850)202 4440   fax
> FL 32502                              (850)291 0667   mobile
> phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
>
>
>
>
>
>


-- 

Regards,

Kingsley Idehen	      
President & CEO 
OpenLink Software     
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen 
Received on Thursday, 1 July 2010 14:42:39 UTC

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