W3C home > Mailing lists > Public > semantic-web@w3.org > December 2012

Re: Well Behaved RDF - Taming Blank Nodes, etc.

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 14 Dec 2012 23:52:00 -0800
Cc: Hugh Glaser <hg@ecs.soton.ac.uk>, Lee Feigenbaum <lee@thefigtrees.net>, David Booth <david@dbooth.org>, semantic-web Web <semantic-web@w3.org>
Message-Id: <57DE3828-4BCB-42E8-B743-5644A651F95C@ihmc.us>
To: ross.horne@gmail.com

On Dec 14, 2012, at 9:41 AM, Ross Horne wrote:

> Thank you for the filtering..
>> On 13 Dec 2012, at 14:41, Lee Feigenbaum <lee@thefigtrees.net> wrote:
>> 
>>> On 12/13/2012 2:00 AM, Pat Hayes wrote:
>>>> Another example: a picture of some celebrity standing next to a horse. I have a URI for the celebrity, but I don't have and don't need one for the horse: and if I were to invent one for each horse, then I could no longer query for retrieval of a picture of that person with "a horse", but would have to remember the URi for each of the bloody horses. But nobody gives a damn about the particular horse.
>>> 
>>> Could you explain this more?

No, but I could retract it. You are right, the querying works fine with or without the blank node. But the other argument still holds: I don't need, and shouldn't have to invent, a URI for something that does not need to be identified. Particularly if in fact I cannot identify the thing in quesiton. Inventing a URI to "identify" an anonymous horse or an unknown room in a building is simply a mis-use of the very idea of a URI as being a universal identifier. 

Pat


>>> Because I'm picturing just doing:
>>> 
>>> SELECT ?photo {
>>>  ?photo a :Photograph ;
>>>       :depicts :ThePerson ;
>>>       :depicts [ a :Horse ] ;
>>>  .
>>> }
>>> 
>>> ...which works fine whether the horse is represented with a blank node or a URI.
>>> 
>>> Lee
> 
> Yes! That's right. Compelling use cases for blank nodes are covered by
> SPARQL. RDF triples *without blank nodes* are adequate and
> understandable by everyone. Let SPARQL do the work.
> 
> The List/Collection use case is covered by Turtle where, like in any
> other language, lists are primitive e.g. ( uri1 uri2 uri3 ). Let the
> primitives be the canonical form and let the bnode encoding be a
> historical curiosity. It was a dubious decision to encode lists in the
> first place.
> 
> This leads to a half page specification for Well-Behaved RDF with
> little or no ambiguity.
> 
> Ross
> 

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Received on Saturday, 15 December 2012 07:52:29 UTC

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