[tmql-wg] Re: [topicmapmail] AsTMa! as TMCL

[Lars Marius Garshol]

* Lars Marius Garshol
|
| We had this issue in OSL as well, and the language allows you to say
| what other classes instances of a particular class are allowed to be
| instances of. This is necessary in order to avoid having people make
| statements like "Puccini is a composer and a city", which might
| otherwise go through with no problem.

* Kal Ahmed
| 
| That sounds like it might be a good basis to start from with
| constraining topics by class.

Having worked with OSL for a while I'd say that for a first attempt
it's pretty good, but it needs more work. I'll be happy to produce a
"what's wrong with OSL" analysis, if anyone's interested, though it
will take some time.
 
| There is a problem here that in the absence of a fixed set of
| classes, no implementation will ever be able to detect all possible
| constraint conflicts at "compile" time in any meaningful way -
| conflicts could only be detected at the time that the topic map
| containing the class instances is presented.

That's true, but I think in the environments people have now you
usually do have a fixed set of classes. I think we'll pretty soon be
at a point where when you merge topic maps you also merge their
schemas and you'll always have a fixed set of classes.

There are architectures that will have this problem, but I'm not sure
it really is that bad.
 
| I can see a couple of useful "usecases" for regex constraints on
| string values such as resourceData and baseNameString, such as
| validating that a "sort-name" variant is actually in the expected
| normalized form, or that a "postcode" occurrence is in the expected
| form etc. I guess that the discussion on regex constraints goes
| hand-in-hand with the discussion on datatype constraints...

Sure, I agree. The choice we have is probably between putting it now
or putting it in later.
 
| Perhaps working from OSL and taking the additional features of
| AsTMA! into account one could have a suitable constraint model to
| start working on expressing in topic map form ?

Makes sense to me. I guess this is how we'll end up putting together
TMCL, unless someone comes up with some bright ideas before work
starts in earnest.

| Something to think about over the christmas dinner perhaps ;-)

Huh? I very much doubt I'll be considering any more complicated issues
than whether to have red or white sauerkraut with my sausages during
that dinner. :)

-- 
Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
ISO SC34/WG3, OASIS GeoLang TC        <URL: http://www.garshol.priv.no >