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

From: Henry Story <henry.story@gmail.com>
Date: Thu, 1 Jul 2010 16:46:45 +0200
Cc: Yves Raimond <yves.raimond@gmail.com>, nathan@webr3.org, Pat Hayes <phayes@ihmc.us>, Toby Inkster <tai@g5n.co.uk>, Dan Brickley <danbri@danbri.org>, Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
Message-Id: <F4F4F816-1C46-4A62-BF74-4C47CC7C07C3@bblfish.net>
To: Kingsley Idehen <kidehen@openlinksw.com>

On 1 Jul 2010, at 16:35, Kingsley Idehen wrote:

> Yves Raimond wrote:
>> Hello Kingsley!
>> 
>> 
>> [snip]
>> 
>>  
>>> 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.
>>> 
>>> 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.
>>>    
>> 
>> It does look like you're already using literal subjects in OpenLink
>> Virtuoso though:
>> 
>> http://docs.openlinksw.com/virtuoso/rdfsparql.html
>> 
>> SQL>SELECT *
>> FROM <people>
>> WHERE
>>  {
>>    ?s foaf:Name ?name . ?name bif:contains "'rich*'".
>>  }
>> 
>> Best,
>> y
>> 
>>  
> 
> Were is the Literal Subject in the query above?
> 
> bif:contains is a function/magic predicate scoped to Literal Objects.
> 
> <people> != "people".
> 
> What am I missing?

Why do you think it is magic? Such a relation makes complete sense.
Given that is is a relation between literals it can be tested without needing
to look at the world. Just like an math:isgreaterThan relation ...

In fact I wonder how much SPARQL could be simplified by thinking of things this
way. Could one perhaps get rid of the FILTER( ) clause?

In any case RDF Semantics does, I believe, 
allow literals in subject position. It is just that many many syntaxes
don't allow that to be expressed,

But there is nothing you can do to stop that happening semantically.  A URI or bnode
can just be names for strings.

And as for it requiring a change to the infrastructure of your DB, it is not clear that
it immediately does, since you can alwasy rewrite


"father" containsLetters 6 .

as 

[] owl:sameAs "father";
   containsLetters 6 .

Henry



> -- 
> 
> 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 14:47:32 UTC

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