Re: [unrev-II] OFFTOPIC? frames, scopes, and functions

From: Eric Armstrong (
Date: Wed Jun 27 2001 - 13:40:25 PDT

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    An interesting post, and one I enjoyed reading.
    I wish I had the capacity to help you with the answers,
    but I wish even more that I had the ability to understand
    the issues!

    What I got from your message:
      * You have a system that aims at unifying and extending
        both RDF and Topic Maps, while solving some problems
        in both.

      * But at the same time, there are representational issues
        that you don't quite know how to solve.

      * Those issues seem to revolve mostly around "nested"
          a) X is true.
          b) Y believes "X is true".
          c) Z thinks that "Y believes X is true" is false.

    Is that about it?

    ppj wrote:
    > This might be a tad off-topic for some members of this list, so I
    > apologise
    > in advance. It is also a bit long.
    > I was wondering if someone could help me with my thinking on the
    > following
    > matters, to let me know if I'm talking rubbish or not. I'm not a comp
    > sci
    > grad, I drifted into I.T. as an auto-didact from other spaces.
    > Once upon a time not so long ago, in venting frustration regarding
    > certain
    > matters, I wrote a specification called SIX
    > ( It was a sketch (and possibly
    > even a
    > bad sketch at that). Essentially I was trying to do three things. One
    > was to
    > free conceptual graphs in XML from the idea of domain-specific syntax,
    > as in
    > RDF, and from all the reasons that went into making that aspect of the
    > syntax of RDF like it is, as I saw that aspect as a bad thing. The
    > other was
    > to break down and make explicit all the relations in Topic Maps and
    > represent them at a single uniform level, exposing them to uniform
    > processing, because my experiences with XTM at the time led me to
    > believe
    > that things were getting murky in that line and I was unable to divine
    > the
    > agendas driving that clearly. Then I sought to generalize from RDF and
    > Topic
    > Maps to a completely arbitrary graph that I hoped could represent both
    > and
    > much more besides.
    > Now the reason I've resurrected mention of SIX on this list is Lee
    > Iverson's
    > desire to be " able to reuse data in a potentially arbitrary set of
    > contexts" (see his mail re: Topic Maps, Ted Nelson, Virtual Files...).
    > I had
    > hoped that SIX would be quite good for this sort of thing if a certain
    > approach to processing were taken. However, I've kept quiet on this
    > matter
    > because I needed to time to figure out whether or not that was the
    > case. I
    > now think my poor brain isn't quite up to the task and I need help. So
    > what
    > follows is some ideas about processing SIX, and in particular about
    > inclusion and reification that I'm hoping someone will start
    > discussing with
    > me.
    > My vision of how one possible processing model for SIX works:
    > The core ideas in SIX: atoms, list of atoms, subject-predicate-object
    > statements, scopes/namespaces, and references. Take the sentence,
    > "Jack Park
    > has a website". And let's conceptually create a namespace like this:
    > Universe < Milky Way Galaxy < Our Solar System < Third Planet
    > where < means the 'is a subscope of ' predicate. So then I can take
    > the
    > scope 'Third Planet' and make assertions like,
    > in-namespace('Third Planet', is-a(person, life-form) )
    > in-namespace('Third Planet', is-a('Jack Park', person) )
    > in-namespace('Third Planet', has-a('Jack Park', website) )
    > So far so good. But now, as is traditional in such matters, I also
    > want to
    > be able to say things like,
    > "Jack Park has a website called 'Thinkalong'."
    > And the way I thought about doing this was by the creation of system
    > references that behaved in certain ways depending on their namespace.
    > So,
    > SREF#123 << in-namespace('Third Planet', has-a('Jack Park', website)
    > )
    > Then,
    > in-namespace(SREF#123, is-called(website, Thinkalong) )
    > where the SREF provides a mechanism for declaring that the namespace
    > of this
    > new statement is the previous one, and that creates the correct
    > association
    > structure for attaching properties.
    > Then there is the small matter of reification. How do I distinguish
    > between,
    > 1) "African elephants are grey" and,
    > 2) "John thinks African elephants are grey".
    > 3) "John thinks the statement, 'African elephants are grey,' is
    > false".
    > My guess for (3) was:
    > SREF#456 << in-namespace('Third Planet', colour('African elephant',
    > grey) )
    > in-namespace('Third Planet', believes(John, is-false(SREF#456) ) )
    > Then for (2),
    > in-namespace('Third Planet', believes(John, SREF#456 ) )
    > The problem with my solution for (3) is that 'is-false(SREF#456)' is
    > another
    > statement in its own right, and that true and false beliefs are
    > mental. So I
    > would have to say something like,
    > SREF#678 << in-namespace( 'Human Thought', is-false(SREF#456) )
    > in-namespace('Third Planet', believes(John, SREF#678 ) )
    > Another alternative is just to declare every statement to be in the
    > namespace of 'Thought' automatically,
    > Thought < Universe < Milky Way Galaxy < Our Solar System < Third
    > Planet
    > and then find some way to define a nifty operator (e.g. 'is-F' and
    > 'is-T')
    > and its attachment to certain predicates like 'believes'.
    > in-namespace('Third Planet', believes(John, is-F(SREF#456) ) )
    > Now, are my beliefs about reification correct, and am I barking up the
    > right
    > tree overall? Are there any huge problems I'm missing?
    > Another nifty thing I had in SIX was grouping. So wherever John is, or
    > ends
    > up, I can effectively say,
    > in-namespace( group('Third Planet', Heaven, Hell), believes(John,
    > is-F(SREF#456) ) )
    > =>
    > in-namespace( 'Third Planet', believes(John, is-F(SREF#456) ) )
    > in-namespace( Heaven, believes(John, is-F(SREF#456) ) )
    > in-namespace( Hell, believes(John, is-F(SREF#456) ) )
    > and also,
    > in-namespace( 'Third Planet', believes(John, group(is-F(SREF#456) ,
    > is-T(SREF#654) , is-T(SREF#777) )) )
    > => John has several distinct beliefs in the same namespace.
    > But compare,
    > in-namespace( 'Third Planet', believes(group (John, Mary, Mungo,
    > Midge),
    > group(is-F(SREF#456) , is-T(SREF#654) , is-T(SREF#777) )) )
    > => Each person in the first group holds the set of beliefs in the
    > second.
    > Now assuming all of that is fine and dandy, I then want to ask, is it
    > possible in logic programming to define functions/rules (and here I'm
    > thinking of reaching for a different syntax for such definitions - see
    > the
    > <ruledoc> element in SIX) to only operate within certain scopes, in
    > much the
    > same way as I've indicated the validity of the statements above?
    > I'm heading in the direction of the graph being everything (XML syntax
    > being
    > almost nothing - the barest of bones), and encapsulation, property
    > assignments, etc. all being controlled by the namespace mechanism.
    > Crucially, I am worried that the SREF + namespaces mechanism I've
    > outlined
    > here and in the SIX spec might break when functions and rules are
    > brought
    > into play on the graph (even though I haven't spotted any problems
    > yet) so
    > if anyone has direct insight into that I'd like to know.
    > I'll leave the mechanism of <wcvar> to one side for now.
    > Any help from anyone, or anyone you know, much appreciated.
    > Thanks in advance,
    > Peter
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