Re: [xtm-wg] Re: parallel development of syntax and concept models

["Steven R. Newcomb" <srn@techno.com>]

[Luis:]
> When you said:
> 
> "(1) UML models for the abstract expression of constraints on
>     APIs to an information set (such as the information set
>     of topic maps), and"
> 
> I don't think the purpose of the UML conceptual model is to express
> constraints on an API.

Maybe not, but it does have that effect.  A UML model represents
decisions and conclusions about what the object classes are.  Those
decisions and conclusions constrain APIs that are built to conform
to them, don't they?

> I think that the conceptual models are to express the Platonic forms
> of topicmaps independent of OS, programming language, or platform.

I agree with you, but I also make the same claim for a set of syntax
constraints.  True, the use of the DTD formalism implies the use of
SGML or XML, but the constraints expressed by a DTD could at least
theoretically apply to other markup syntaxes, as well.  Suppose we
used sets of BNF linguistic productions instead of DTDs.  Wouldn't it
then be just as true to say that "the BNF productions are to express
the Platonic forms of topicmaps independent of OS, programming
language, or platform"?

> I know that by definition that is impossible to accomplish. But, at
> least that is the purpose. I think that is where we disagree. Our
> views of the usefulness of the conceptual model is very different.

OK.  I see that we don't agree about this.  I would ask you a
question: Is there nothing about the Platonic forms that is not
captured in a UML model of them?  It worries me that you don't see any
distinction between your preferred expression of the Platonic forms (a
set of object classes) and the Platonic forms themselves.

> Also, i think an object model is more abstract than a DTD. You can
> use a DTD as a modeling language but it is too ambiguous to define a
> structure by itself.

This statement, while true, does not speak to my point.  I'm willing
to grant that there are certainly ways in which an object model is
more abstract than a DTD, if you're willing to admit that:

(1) Both DTDs and sets of object classes are both expressions of a
    higher-order abstraction (the information set, aka the Platonic
    forms), and

(2) DTDs and sets of object classes should be designed with different
    engineering constraints in mind, because their scopes and fields
    of application are different.

I do not claim that one is more or less abstract than the other, and I
do not claim that one is *not* more or less abstract than the other.
What I claim is that this whole question of relative abstractness is
irrelevant, as a practical matter, and extremely misleading, because
their scopes and fields of application are orthogonal, and because it
makes it far too easy to succumb to the temptation to ignore the
distinction between

(1) how and why something is being said about an idea, and 

(2) the idea itself.

This is a really big and really important distinction.  To fail to
make this distinction is to make the same kind of error that is made
when one confuses:

(1) a generally accepted scientific theory

with

(2) the truth.

Forward progress is greatly hindered, and even prevented, when we fail
to make these kinds of distinctions.  Making these kinds of
distinctions allows us to make progress *in spite of* our inability to
perceive the truth directly.  First of all we must understand that our
whole perceptual and cognitive apparatus, including our system of
beliefs and our latent assumptions, are almost certainly flawed.
Having understood this, we are in a position to adapt appropriately to
evidence that we've been wrong all along, or that there are depths of
understanding of which we have been unaware.

I personally believe that dialogue between the modeling group and the
syntax group will bring a greater understanding of the basic ideas
here.  I do not believe that either group's models will be the truth,
or even that the combination of all models will be the truth.  The
truth is much more elusive and intangible than that.  But the truth
*does* exist, it *does* await further unfolding, our apprehension of
it *will* improve.  That improvement will be greater and sooner by the
use of reasonable and reasonably diverse approaches to expressing it,
especially in cases where multiple diverse expressions are *required*.

-Steve

--
Steven R. Newcomb, Consultant
srn@techno.com

voice: +1 972 359 8160
fax:   +1 972 359 0270

405 Flagler Court
Allen, Texas 75013-2821 USA

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