W3C home > Mailing lists > Public > semantic-web@w3.org > July 2010

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

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 30 Jun 2010 21:40:03 -0500
Cc: Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
Message-Id: <CE577353-D11A-4323-8C1A-575A5796B56B@ihmc.us>
To: Kingsley Idehen <kidehen@openlinksw.com>

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


> 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
Received on Thursday, 1 July 2010 03:11:32 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 21:45:37 GMT