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Re: Turtle, Qurtle, Super-Turtle, N-Triple, N-Quads, Trig - BC and Scope

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 2 Mar 2011 13:48:40 -0600
Cc: RDF-WG <public-rdf-wg@w3.org>
Message-Id: <2EDA7536-6F41-4F7B-8490-0400FD7CD9AF@ihmc.us>
To: nathan@webr3.org
A few quick semantics answers.

On Mar 2, 2011, at 12:55 PM, Nathan wrote:

> Hi All,
> Okay, I'm lost, as to what's what and what is in scope, out of scope, possible and not.
> Is B.C. for turtle (data and consumers) to be maintained?
> Are Quads to be adopted?
> - for turtle? (trig?)
> - for some kind of qurtle?
> - for some kind of super-turtle?
> - for n-triples?
> - would quads change the semantics?

Depends on what the fourth item is supposed to mean. If it is just a loose syntax marker, then no. If it is supposed to change the meaning of the RDF in some way (eg by encoding a time-stamp) then yes. If it is just a graph/g-box name, then yes, but so minimally that it will not cause any pain. (And this semantic extension is already fully worked out in the named graph paper and the ISO CL standard.)

> just the concepts?
> - quads = named g-box, or just some "spare" 4th param?
> Is it even possible for us to do something not the same as current turtle? (charter wise)
> If we can't change turtle, and can't do super-turtle or qurtle, why and how can we even discuss graphs of any form?
> Syntax sugar like ^ prefix, in scope?
> Quoted Graphs, in scope?
> - if yes, what to they resolve to in the RDF semantics? how would that work?

Semantics would need to be extended but it would be easy to do. 

> Graph Literals?
> - what's the difference between quoted graphs?
> variables?

Variables?? Do you mean as in SPARQL? (If not, I really don't want to hear about variables... semantic nightmare, it sounds like.) 

> changes to the semantics?
> - if no, can changes like g-box be introduced without being in the semantics?


> changes to the concepts?
> - if yes, what about B.C. with RDF/XML? existing deployed data and processors? how can they change but the semantics not?

Well for example (only an example) putting literals in subject position is a huge change to parsers but invisible in the semantics (it would already handle that case without change. The inference rules would actually get simpler.) There are probably other cases like this as well. 


> align turtle with sparql?
> - if yes, how without variables, subject literals and all the other bits?
> Sorry, I feel like we need to know what definitely cannot happen, what definitely can and what's a grey area, for this WG.
> Cheers,
> Nathan

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Received on Wednesday, 2 March 2011 19:49:21 UTC

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