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Re: Contexts (not again!)

From: Richard H. McCullough <rhm@cdepot.net>
Date: Thu, 14 Nov 2002 09:36:04 -0800
Message-ID: <001801c28c04$4efee280$bd7ba8c0@rhm8200>
To: "Graham Klyne" <GK@ninebynine.org>
Cc: "Danny Ayers" <danny666@virgilio.it>, "RDF-Interest" <www-rdf-interest@w3.org>
1. KR is "working software".  Click on "knowledge" below my name, and you can download "Knowledge Explorer" for Windows or Linux.  My first version of KR was in 1996, and I have been evolving it as I apply it to new domains.  In the last 2 weeks, I have added example KR versions of Dublin Core, RDFS, OWL, etc.
2. "Context is the relationship ..." doesn't sound right to me, but I need to read Tim's "Design Issues".  I skimmed it once, but I skipped past "formulae" and thus didn't notice the "context" part.
============ 
Dick McCullough 
knowledge := man do identify od existent done
knowledge haspart list of proposition

  ----- Original Message ----- 
  From: Graham Klyne 
  To: Richard H. McCullough 
  Cc: Danny Ayers ; RDF-Interest 
  Sent: Thursday, November 14, 2002 8:14 AM
  Subject: Re: Contexts (not again!)



  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 12:36:09 GMT

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