A Line in the Declarative Syntax Sand(Was: XML complexity, namespaces (was WG))

Rick Jelliffe ricko at allette.com.au
Sun Mar 28 13:31:26 BST 1999

From: David Megginson <david at megginson.com>

 >Rick, you're still pointing to implementation details rather than
>abstract modelling.  Try to express the question in terms of the thing
>being modelled -- for example, at a project meeting, the system
>architect might ask the following question:
>  Can SGML and XML both model a reference to a photograph, providing
>  the width, height, and colour depth?
>The answer, of course, is 'yes'
(Sad and somewhat mysterious story deleted: what is the point? That
anyone who discusses what information is implied by XML markup is a
boofhead? In any case, the forum here is not XML-DEV, not a company
design meeting.)

Huh? At some level of abstraction all distinctions disappear: XML
becomes the same as ethernet when the abstraction is "things that can
transport characters".

Dave seems to be  saying that
    ( X , X, X )
is the same as
     ( X, what-he-said, what-he-said)

I agree that (to bend LISP out of shap)
       eval( X, X, X)
is the same as
       eval(X, what-he-said, what-he-said)
but Dave seems to be  saying that the fact that two things (pointed to)
are the same is not "information". That seems an extraordinary claim.

    <owner id="j1">john</owner>
    <dog owner="j1">rover</dog>
    <dog owner="j1">rex</dog>

encodes more information than

    <dog owner="john">rover</dog>
    <dog owner="john">rex</dog>

unless there is schema defininion in effect somehow somewhere that the
strings in owner attributes follow the rule one-name=one-owner. In the
first version, that information is part of the model. In the second, it
is not.

Rick Jelliffe

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