[sc34wg3] Conformance

Jan Algermissen sc34wg3@isotopicmaps.org
Sun, 27 Apr 2003 21:03:03 +0200

Lars Marius Garshol wrote:
> * Jan Algermissen
> |
> | For me "the same abstract structure...in the form of a data model."
> | means that N0396 defines a 'conceptual data model' or call it
> | 'abstract information structure'.
> I agree with the latter. The first I don't know what is. I'd be very
> careful with that term, since it seems to conflate two different kinds
> of models into a single one.
> | What I am up to is to find the purpose that this structure
> | fulfills. Since it does not make sense to use it to constrain the
> | internals (I could create an implementation that never actually
> | performs a merge internally but makes it look as if it did from the
> | outside) then what is it good for (not the SAM as a whole, just the
> | data structure)?  Is it purely a matter of providing a language to
> | 'say' the important stuff (e.g.  merging rules)? Is it purely
> | illustrative?
> I explained this to you in the email you just replied to:
> * Lars Marius Garshol
> |
> | The SAM is *not* a conceptual model, it's the instrument we use for
> | defining the interpretation of the two syntaxes, the relationship
> | between them, and we will also use it to define a conformance testing
> | tool (CXTM), and finally it will be the foundation of the constraint
> | and query languages.

I am only concerned with the abstract information structure (which != SAM).
So, are you saying that this struture is "the instrument we use for
defining the interpretation..."?

> Isn't this clear? N0278 and N0323 say the same thing.
> | To take this out of TM context: What purpose does the entity
> | relationship model fulfill in RDBMS land?
> It's the mathematical foundation of the ER modelling formalism, 

I am talking about the data model only, not relational calculus nor
relational algebra. Suppose there was only Chen's original paper, no
more - what's the purpose the data model fulfills?

> which
> is intended to help people produce better information models. The ER
> model is used to connect ER diagrams to the relational data model.

Anyhow, if the abstract information structure of N0396 (or N0393) is not
constraining the application internals, what does it mean to define merging
rules in terms of that structure?

It seems to me we are saying something like: "A conforming application must
appear (to the 'user') as if it actually implemented the abstract information
structure."  But, duh- what does that *mean*?

Also, N0396 says:

"Merging is a process applied to topic maps in order to reduce the number of
redundant information items representing the same information."

What is the meaning of this, if we are not interested in the internals?
(I absolutely don't care how many objects the Omnigator uses for a single
subject internally, all I want is a  certain behaviour 'to the outside')

So, what is it that we are constraining at the N0396 or N0393 level?


> --
> Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
> GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >
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Jan Algermissen                           http://www.topicmapping.com
Consultant & Programmer	                  http://www.gooseworks.org