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Re: Contexts (not again!)

From: Graham Klyne <GK@ninebynine.org>
Date: Thu, 14 Nov 2002 16:14:13 +0000
Message-Id: <5.1.0.14.2.20021114160433.03da3d20@127.0.0.1>
To: "Richard H. McCullough" <rhm@cdepot.net>
Cc: "Danny Ayers" <danny666@virgilio.it>, "RDF-Interest" <www-rdf-interest@w3.org>

At 06:06 AM 11/14/02 -0800, Richard H. McCullough wrote:
>I'm having trouble understanding your notion of "context".

As I am yours.   The term has been much abused (and I don't excuse myself).

Because it's working software, Notation 3 is probably a useful common 
ground, with its notions of formulae (roughly: collections of statements) 
and context "Context is the relationship between a statement and the 
formula it is directly part of" [1].

I don't fully understand the last bit, but the idea of context as a 
relationship rather than a thing seems to sidestep the discussion of 
forward/backward view of these things.

#g
--

[1] http://www.w3.org/DesignIssues/Notation3

>Paraphrasing your three properties:
>     Resource has context = Statement
>     Statement has contains = Resource
>     Bag has contents = Resource
>
>This seems backwards to me.  I think of context
>as follows:
>     Statement has context = cname
>     cname is List of Statement
>
>Remarks:
>1. Although a Bag of Statements will work in some
>cases, I think that a List is necessary in general.
>2. If you want to include actions (as opposed to static
>Properties), then context should include space and
>time.
>3. In my KR language, I put the context before the
>Statement (I call the static context "view")
>     at view = cname { Statement }
>My static Statement is written as
>     subject has predicate = object
>============
>Dick McCullough
><http://www.volcano.net/~rhm>knowledge := man do identify od existent done
>knowledge haspart list of proposition
>----- Original Message -----
>From: <mailto:GK@ninebynine.org>Graham Klyne
>To: <mailto:danny666@virgilio.it>Danny Ayers
>Cc: <mailto:www-rdf-interest@w3.org>RDF-Interest
>Sent: Wednesday, November 13, 2002 4:59 AM
>Subject: Re: Contexts (not again!)
>
>
>
>I think the "dark triples" approach fizzled out.  My take is that we're not
>ready to standardize context mechanisms yet, but  still have hopes of
>prototyping my ideas in this area, which aren't vastly different from what
>I think you're describing.  I think that reification, or a variation of it,
>can be used (in a prototype implementation) to encode the triples that
>aren't asserted.
>
>In the longer run, a standard solution may call for something more
>"hard-wired", with scope for optimization.  I think this might come about
>without invalidating/isolating the
>prototype approaches.
>
>#g
>--
>
>At 10:59 PM 11/2/02 +0100, Danny Ayers wrote:
>
> >Hi folks,
> >
> >Did any kind of consensus, or even decision (!?) result from Pat's 'dark
> >triples' suggestion [1] etc. earlier in the year (or any other of the
> >familiar context discussions)? I've had a look through the archives and as
> >usual the threads are hard to follow. I'm wondering because I'm running up
> >against this thing again.
> >
> >If there isn't anything sorted or on the cards in this area, I'd appreciate
> >comments on the following first crack hackiness for a context vocabulary.
> >I've not really got a grip on the reification angle with it yet, but the 
> use
> >I'm after is really just to be able to tag triples (make 'em quads in
> >memory), and it'd be nice to do it in a moderately sound fashion.
> >
> >Just three terms (the pseudo-schemas are undoubtedly way out) : context,
> >contains, contents
> >
> >*context* - a group of statements (identified collectively by a single URI)
> >with which a particular statement can be associated. In practice this would
> >usually be
> >
> >[triple]-context->[RDF file]
> >
> >Property "context"
> >    domain Resource
> >    range Statement
> >    inverseOf contains
> >
> >
> >*contains* - the other way around,
> >
> >[RDF file]-contains->[triple]
> >
> >Property "contains"
> >    domain Statement
> >    range  Resource
> >
> >
> >*contents* - a list/collection whatever of (references to) the 
> statements to
> >be identified by a given URI (i.e. the triples in a file)
> >
> >Property "contents"
> >    domain Bag
> >    range Resource
> >
> >[RDF file]-contents->[s1, s2...]
> >
> >The first of these is probably all that I'd need, but the second 
> insisted on
> >coming along. The third heard there was a party.
> >When I started thinking of a way around this, the first thing that came to
> >mind was a Context class, akin to a collection/bag, instances of which 
> could
> >be used to identify a file but with this it seemed to get messy a lot
> >quicker...
> >I'm pretty sure I'm badly conflating the unreified/reified triples here, 
> and
> >it does seem like it goes a bit beyond what can be expressed in RDF(S) 
> alone
> >(i.e. a minilayer on top) but I'm hoping that something usable won't be far
> >away. I'm willing to bet there's something along these lines already, but I
> >can think of worse ways to spend a Sunday evening.
> >
> >Cheers,
> >Danny.
> >
> >[1] 
> <http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Mar/0253.html>http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Mar/0253.html 
>
> >
> >
> >-----------
> >Danny Ayers
> >
> >Semantic Web Log :
> >http://www.citnames.com/blog
>
>-------------------
>Graham Klyne
><<mailto:GK@NineByNine.org>GK@NineByNine.org>

-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Thursday, 14 November 2002 11:22:37 GMT

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