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

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

From: Nathan <nathan@webr3.org>
Date: Wed, 30 Jun 2010 22:05:35 +0100
Message-ID: <4C2BB19F.5000500@webr3.org>
To: Pat Hayes <phayes@ihmc.us>
CC: Toby Inkster <tai@g5n.co.uk>, Dan Brickley <danbri@danbri.org>, Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>, Tim Berners-Lee <timbl@w3.org>
Pat Hayes wrote:
> 
> On Jun 30, 2010, at 11:50 AM, 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.
> 
> I wholly agree. Allowing literals in subject position in RDF is a 
> no-brainer. (BTW, it would also immediately solve the 'bugs in the RDF 
> rules' problem.) These arguments against it are nonsensical. The REAL 
> argument against it is that it will mess up OWL-DL, or at any rate it 
> *might* mess up OWL-DL.
> 
> The Description Logic police are still in charge:-)

As you know I'm pretty new to this, relatively, but here's a thought I 
can't get rid of.

Keep RDF as loose as possible at the core semantic level (subjects as 
literals etc).

Have the semantics of each triple defined by it's predicate (each 
property can define it's own domain and range etc)

This may also allow for using rdf as a data model, and there's no reason 
every triple must be dereferencable etc.

Above this, afaict, no reason why each serialization can't have it's own 
strong semantics too, like HTML+RDFa can instruct that a URI should be 
embedded and so forth (<img src=).

Just a thought.. I'm sure you can tell me why I'm wrong

re OWL DL, does it have to consider every triple in a 'graph'?

Nathan
Received on Wednesday, 30 June 2010 21:06:37 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 21:45:36 GMT