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

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Fri, 02 Jul 2010 07:52:53 -0400
Message-ID: <4C2DD315.4010505@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 Jul 1, 2010, at 9:42 AM, Kingsley Idehen wrote:
>
>> 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?.
>
> "subject' refers to the first element in a triple, "object" to the 
> last. One might as well call them 'first' and 'third'. The names
> 'subject' and 'object' are used purely for convenience, and have no 
> formal or semantic significance.
>
>>
>> If they are the same thing, why on earth do we use Names (with 
>> implications) to describe the slots in an RDF triple?
>
> I do not understand the question here well enough to provide an 
> answer. Have you actually read the RDF spec documents? The RDF syntax 
> model and the semantics?

You don't understand the question enough to provide an answer, but you 
are able to compute an assessment of spec assimilation. WOW !!
>
>>
>> I've only once seen the RDF triple referred to as O-R-O (by @danbri) 
>> i.e., Object-Relation-Object.
>
> IF you read the specs, however, it is abundantly clear that this is 
> what an RDF triple means, viz. that a relation holds between two 
> objects (I prefer "things", but....).

Exactly!

So why: Subject-Predicate-Object  (SPO) everywhere re. RDF?

O-R-O reflects what you've just described.

Like many of the RDF oddities (playing out nicely in this thread), you 
have an O-R-O but everyone talks about S-P-O.

"Subject" has implicit meaning, it lends itself to describing stuff.  If 
I recall, RDF stands for: Resource Description Framework.

I guess "Description" also means nothing?

>
>>
>> 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.
>
> Why do you say this? It is certainly as much a name as, say, "Patrick 
> J. Hayes". It is a well-formed string which denotes something, and its 
> denotation is perfectly clear, in fact computable. So, it is a name. I 
> challenge you to specify what you mean by "Name" in such a way that it 
> excludes literals as names, other than by simply reiterating your bare 
> claim that they are not.

I mean an unambiguous Name for a Web of Semantically Linked Data.

"Patrick J. Hayes" simply doesn't cut it as an unambiguous name within 
the aforementioned Web.


>
>>
>> **
>> 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 :-)
>
> I see it the way the RDF specifications describe it. I am genuinely 
> not quite clear how you see it, but it seems to have very little to do 
> with the way it is specified. Perhaps you would be better off using 
> something other than RDF.

No comment, really !


Kingsley
>
> Pat
>
>
>> 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
>>
>>
>>
>>
>>
>
> ------------------------------------------------------------
> 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 Friday, 2 July 2010 11:53:23 UTC

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