W3C home > Mailing lists > Public > public-powderwg@w3.org > July 2008

Re: Blank nodes in descriptor sets - a proposal to deal with this using Occam's Razor

From: Stasinos Konstantopoulos <konstant@iit.demokritos.gr>
Date: Thu, 17 Jul 2008 14:56:50 +0300
To: Phil Archer <parcher@icra.org>
Cc: Public POWDER <public-powderwg@w3.org>
Message-ID: <20080717115650.GD4871@iit.demokritos.gr>

On Wed Jul 16 16:14:29 2008 Phil Archer said:

> Thanks for putting even more time into this.
> If I understand you correctly it would be fair to allow this:
> <ex:material>
>   <ex:Wood>
>     <ex:colour>brown</ex:colour>
>   </ex:Wood>
> </ex:material>
> but we should explain that this means that "there should be a resource  
> out there which is of the type ex:Wood that has the color brown, and  
> that this is the value filler for our properties." Although this may be  
> semantically valid, such a construct is usually inappropriate for use in 

Indeed. So dropping this from descriptions would be no big loss, as it
is hardly expected to be used. But would be a big loss if also dropped
from attribution elements, disallowing constructs like:

      <foaf:phone rdf:resource="tel:210650"/>

We could, however, mention in the text that it is bad practice to
re-define entities that already have FOAF or DC descriptions of

> Giving the node an ID using rdf:about effectively creates a new  
> vocabulary term that is duplicated every time the POWDER document is  
> processed and although, again, this may be useful in some circumstances  
> it's generally better to use a pre-defined term if possible.

Most definitely better, if possible. The question is about situations
where there is no appropriate pre-defined vocab item.

> Finally, since POWDER transports RDF/XML, it is not unreasonable to  
> expect a POWDER Processor to be do at least minimal processing of RDF  
> and not just always as XML.


Note: I will only be "mildly on-line" starting today and during next
week and "really off-line" the week after that, but I think that we are
converging, so I am not wooried that I am leaving s'thing important in
the middle.

About owl:Ontology, like I wrote yesterday, I would like to leave the
rdf:Description door open until after summer vacations, but if the group
feels this should be resolved by LC, then by all means go ahead.

Received on Thursday, 17 July 2008 11:57:32 UTC

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