RE: [xtm-wg] XTM-CMS: Topic associations

["Michel Biezunski" <mb@infoloom.com>]

> It does not really, since there is currently no way of saying "all
> instances of the is-married-to' association must have exactly one
> 'husband' anchor role and one 'wife' anchor role".

This is a different issue. It has to do with how your topic map description
is constrained, and what internal consistency rules you apply. This is not
covered yet by the standard, and should be studied at an application level,
or as part of a TM-schema language project, to be defined.

In the ISO standard, you can constrain your own topic map architecture by
declaring your
own DTD. But the mechanism enforcing constraints and rules on the base of
the DTD structure
(or even XML schemas) is probably unsufficient for what topic maps need to
represent. Therefore
I don't think anybody wants to preserve this for XTM and it seems that
consensus goes to the
wide open representation of topic maps, whatever rules have been applied to
create it. It is the
result that we interchange, not the way it has been created.

> So while you can certainly specify class membership in the current
> standard, you can not restrict the structure of class instances in any
> way.
>
> | - Now, if you want to say something about an instance of the
> | marriage, e.g.  the one between John and Jackie Kennedy, you
> | consider that the association you are talking about is an occurrence
> | of the topic "Marriage of John and Jackie Kennedy", that might have
> | many other occurrences elsewhere, a definition, an identity, etc.
>
> In theory this is possible, but is there any software that actually
> implements this? If so, how is it implemented? Also, the standard does
> not say anything about what implications this has for the data model
> or how such special-case occurrences are to be treated.
>
> So I'm not sure that this can really be done in any useful way at the
> moment.
>
> | The difference is that in the class case, the topic representing the
> | class is automatically generated within the topic map,
>
> What do you mean by this?

When you say:
<assoc type="marriage" ...>
...
you must have in the same topic map another topic whose id is marriage, even
if
it has no occurrence, but just a name.

<topic
id="marriage"><topname><basename>marriage</basename></topname></topic>

This is the only way to know that when you say type="marriage" you're
actually speaking
of "marriage", because you can document it yourself, put an identity on the
topic if it's a public topic,
and do whatever you want to do on topics.

For the clarity of the example,  I prefer this expression (which is actually
identical to the previous):
<assoc type="xxyushjs9e3" ...>

<topic
id="xxyushjs9e3"><topname><basename>marriage</basename></topname></topic>

Michel
==========================================
Michel Biezunski, InfoLoom, Inc.
Tel +33 1 44 59 84 29 Cell +33 6 03 99 25 29
Email: mb@infoloom.com  Web: www.infoloom.com
==========================================


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