Re: +blank node identifiers was- Re: [Graphs] Fwd: Comments on "SPARQL 1.1 Uniform HTTP Protocol for Managing RDF Graphs"

On Mar 18, 2011, at 6:15 PM, Nathan wrote:

> Gavin Carothers wrote:
>> On Fri, Mar 18, 2011 at 2:25 PM, Nathan <nathan@webr3.org> wrote:
>>> Nathan wrote:
>>>> Sandro Hawke wrote:
>>>>> On Fri, 2011-03-18 at 19:22 +0000, Andy Seaborne wrote:
>>>>>> Is g-snap->g-text is just a function of the content type?
>>>>> Well, probably, for our purposes, I think so. There's a trivial case
>>>>> where it's not: the  arbitrary non-semantic
>>>>> variability in serialization, eg whitespace.  So, some notion of
>>>>> equivalence class of g-texts may be important.
>>>>> 
>>>>> There's a related problem I don't know if we can or should address,
>>>>> which is how to deal with websites which use cookies or other
>>>>> information (IP address, browser sniffing, etc) to customize content.
>>>> I was going to raise that, it's where the "resource state" http/rest story
>>>> and the rdf "snapshot" story both breaks down.
>>>> 
>>>> Perhaps we should just scrap that story early on and have Named-G-Box = (
>>>> <u>, GB ) where GB = { gt1, gt2, gt3, ... }
>>>> 
>>>> Where gt* are g-texts, and GB is a g-box. A g-box being a set of g-texts
>>>> over time. And of course a named-g-box is just a GB associated with a URI.
>>>> 
>>>> If we need g-snap, which I'm sure we do, then perhaps each g-text
>>>> encodes/serializes a g-snap, and several g-texts may all encode/serialize
>>>> equivalent g-snaps, but that requires g-snap equality to be determined.
>>>> 
>>>> O, actually I quite like that, then all g-snap's are anonymous abstract
>>>> sets of rdf triples, and it's the set of g-texts (g-box) that is associated
>>>> with a name.
>>> Ahh, then blank node identifiers would be a property of the g-text, and the
>>> g-texts can be associated with a named-g-box, which would surely set blank
>>> node identifier scoping to the named-g-box level?
>> I think the issue with that is the idea of union graphs, and as Andy
>> mentioned on the telecon how that interacts with inference graphs. I'm
>> honestly not sure of what to do about blank nodes with graphs at all.
>> In all my use of named graphs I've always ended up avoiding them like
>> the plague.
> 
> I think I agree, and also that the above perhaps says that blank node identifiers are in fact little more than serialization/g-text specific features that let you reassemble a graph - that is, not all serializations would need blank node identifiers, and they have no meaning in rdf semantics or concepts.

Exactly right.

> 
> That said, I feel like there's something/some-detail I'm missing, need to think on it harder.

I don't think so, you have got top the nub here.

Pat

> 
> Best,
> 
> Nathan
> 
> 

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Received on Saturday, 19 March 2011 19:36:51 UTC