Eric Armstrong wrote:
> Ignoring XML and anything remotely like it. What would you use?
The short answer is to at least start with William Kent's ROSE/STAR
model defined in his book "Data & Reality" implemented in whatever
http://home.earthlink.net/~billkent/catalogmain.htm#TOPICS IN SEMANTIC
For something even easier, just start with some tuple-space system
or like IBM's T-spaces. http://www.almaden.ibm.com/cs/TSpaces/
Gelernter of Linda is the same guy who is involed with LifeStreams.
The slightly longer answer is that any sort of Knowledge
Representational system is a sort of AI, even if it is designed a
primarily augmenting rather than acting independently. One needs to do
domething like create a system with multiple levels of knowledge about
knowledge, where a representation at any level can be used to observe,
browse, or modify the representation at a lower level (introspection,
self reflection?). For a shallow example, one might have a set of
knowledge structure in a DKR which define a GUI interface to interact
with the repository, but you might then use that GUI to rework the
underlying knowledge structures to define new GUI. A deeper example
entails knowledge structures that define search and summary techniques
which produce new knowledge. However, at the same time the lower levels
need to generate the behavior of the higher levels, but in a
compartmentalized way so that a compartment at the upper level can
operate on a different compartment of the lower level than the one that
sustains it. On a practical basis, an implementation of something like
this was VisualWorks Smalltalk's (unfortunately killed) "firewall"
concept, where a set of development tools could be used to develop new
development tools, those tools being behind a "firewall" in a logical
(not network) sense.
My longer point is that the knoeledge management / representation
problem is a deep one, and XML doesn't address it in a serious way, and
confuses the subject by the hype making it sound like XML does address
the topic of knowledge representation in a serious way. However, sorry,
as an alternative (not to XML, but to lots of hard work mucking in these
K.R. fields) I have no easy answer. There are person-millenium of AI and
cognitive science work years at my feet and I can't really point to much
of it as being immediately useful. In general, much of it is generally
useful for understanding the difficulty of the problem. I'd think
Hofstader's work on Fluid Concepts and Creative Analogies is a great
source of ideas for a good example of the better stuff.
We have to accept that much work knowledge representation work (creating
formats and content) will need to be done on whatever platform we
choose. Further, to be practically useful, we need to pick some problems
to address which can be addressed relatively easily, but ideally
addressable in such a way as the approach can later be revised and
I think the decision for tools to build with needs to be based more on:
* active development communities
Squeak, Python, Common Lisp (less so) are interesting choices.
I'm starting to think Squeak might be the best choice for prototyping
(for me) given that it is completely cross-platform and open. It's
cross-platform GUI does the best job of addressing the DKR design
requirement of shareable screens.
> > ...
> > The point is to create a DKR/OHS flexible enough to deal with this
> > issue of representations changing over time as users needs change.
This is a question AI workers and Knowledge Management workers spend
years studying, and more years working on, to make solutions that are
incomplete. There is no easy answer yet (if ever).
However, the mainstream AI community is starting to improve in this
area. For example, at a talk last year by Marvin Minsky he went on at
length about the need for multiple representational strategies for
problem solving. He argued the human mind may perceive problems using
five or six strategies (ex. geometrical reasoning, formal logic,
heuristic rules of thumb, pattern recognition, semantic networks,
others) and continuously picks the best one at the time to progress in
Maybe what we need is a overview of the AI and knowledge management
fields and how each area or major problem/topic would affect a DKR/OHS.
Also, what will evolve over time for an OHS/DKR project is a set of
useful code that can manipulate data strucutres that are related to
knowledge representaion. We might also wish to have a survey of such
> > And to take things further, why invent XML when one could instead just
> > use LISP to the same effect (and with less bytes)? Lisp is used all
> > the
> > time to define representations such as:
> > (user
> > (ID 100001)
> > (name "Grampa Muenster")
> > (address "13 Mockingbird Lane"))
> If we're only talking about data representations, this could easily
> be done in XML. One is not required to use DTD-validation when parsing
> an XML structure. So one can easily add other name/value pairs, without
> being constrained by a DTD. The only time a DTD comes into play is when
> you *want* to enforce restrictions. And there are times when you want
True. However, as time goes on, any restrictions will become obsolete.
One needs a representational system that can adapt to user needs. And
while XML, could be a part of that solution, the important issues go
beyond that -- to standards creation and revison and communication, and
to to coin a phrase "data upgrading".
> > Lisp can easily parse this which defines a valid LISP list, and we can
> > define LISP programs with related data that validate such
> > representations. That is what AI programmers have been doing for
> > decades.
> Certainly. Validating the structure is always possible in the program,
> with Lisp, XML, or any other data representation. DTD-validation is only
> a convience that permits taking that burden off the programmer, when it
> is desirable. There is also an intermediate ground. An DTD can be
> written so that any number of pairs of name and value elements can
> occur, so what you see is
> <name>ID</name><value>100001</value><name>address</name>... etc.
> The DTD can then ensure that the name/value pair restriction is never
> violated, but the values can be anything we want. Again, validation is
> not required, so even this restriction does not have to be enforced.
But DTD validation only gets you so far. And I believe with XML DTDs
there are some limits to the nature of the structures you can define
(which SGML does not have.)
Any library (for Lisp, Smalltalk, etc.) can define a DTD like syntax (or
something better) to easily define limits on valid representations.
The deeper issue is that rather than focus on ways to limit
representations (DTDs) we need to focus on ways to transform, extend,
and simplify representations as needed (sort of along the multi-level
approach I mentioned earlier).
> > However, in my opinion, the investment in learning and
> > using these other systems (Smalltalk, Lisp) is worth it.
> No argument there. Maybe some of the flexibility you desire comes from
> the ease of manipulation in those languages, rather than from the data
> structures themselves?
Yes. That is big part of the issue. Any DKR/OHS will need to be more
than a bunch of passive data in a database. It will need many programs
to do things to that data to make new data (search, format, summarize,
repackage, interpret, transfer, upgrade, etc.).
A more important issue than data transmission format (the one XML tries
to address) is to build a robust platform for doing those algorithmic
things. As a first cut one picks a language and does something. As a
deeper approach, one tries to represent the knowledge and algorithms in
an abstract enough way as to be ideally programming language neutral or
at least programming language retargetable (generating whatever code in
whatever language as needed).
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