W3C home > Mailing lists > Public > public-lod@w3.org > February 2012

Re: Metadata about single triples

From: Bob Ferris <zazi@smiy.org>
Date: Wed, 22 Feb 2012 18:21:05 +0100
Message-ID: <4F452401.5010608@smiy.org>
To: public-lod@w3.org
Hi Carsten,

On 2/22/2012 5:51 PM, Carsten Ke▀ler wrote:
> Hi Bob,
>
>> At a first glance, your ontology looks very interesting and well designed.
>
> thanks, we are doing our best ;)
>
>> So there might be the (rather old) need for
>> statement identifiers, i.e., a URI (or maybe also a bnode) for identifying a
>>   single triple and to be able to describe external context information. You
>> can find my proposal at the RDF WG comments mailing list, see [2].
>
> Thanks for these pointers. These ideas all make sense, however, we are
> also concerned about the implications in practice, i.e., we have to
> make sure that whatever approach we pick is supported by triple
> stores. I do see that your proposal of having an identifier makes
> sense at a conceptual level, but in practice, does it matter if we end
> up with named graphs that may only contain a single triple in some
> cases? I don't think it does, but maybe I'm missing something.

I think it matters, because Named Graphs unnecessary fragment complex 
descriptions into (very) small piece due to their provenance 
descriptions*. So when you would like to query this complex description 
at once you may have to include many Named Graphs. This makes the SPARQL 
query rather complex.
A current workaround is to duplicate this fragmented knowledge into a 
default graph to be able to easily query such complex descriptions 
(without their provenance information). This increases the maintenance 
costs as well and the (originally) related knowledge is now decoupled.
On the other side, many triple store vendors are already utilising 
statement identifiers internally. So why not utilising them externally 
as well by introducing URIs instead of internal identifiers.
I really believe that would be a win-win situation for all participants.
Please also remember my proposed utilisation of statement identifiers 
should be optional, i.e., if someone does not need this, one does not 
have to utilise it.

Cheers,


Bo


*) Furthermore, you do not really have the chance to relate knowledge 
that is copied into another Named Graph, but which is practically the 
same and belongs together, because you have the enclosure of every Named 
Graph (you can read many long discussions on the whole named graph topic 
at the official RDF WG mailing list).
Received on Wednesday, 22 February 2012 17:21:45 UTC

This archive was generated by hypermail 2.3.1 : Sunday, 31 March 2013 14:24:37 UTC