Every thing is a 'thing'

* Robert Barta
>
> What about something more philosophic ;-)

I've no trouble with that, but a new subject would be nice...

>    TMDM defines the concept subject, but it say nowhere that all
>    things in the map (topics and associations, for instance) are
>    'subjects'. And it also does not say that all classes are
>    subclasses of 'subject'.

If we do this we should do it in the TMDM -> TMRM mapping.

>    Now, what should a TMQL processor deliver here:
>
>       select $thing
>       where
>          $thing isa tm:subject

There are several possibilities here:

  (1) All topics in the topic map
  (2) All Topic Maps constructs in the topic map
  (3) All constructs + all values in the topic map
  (4) All constructs + all values in all value spaces for all datatypes
  (5) All values that could theoretically exist
  (6) An error :-)

Strictly speaking (3) is the most logically consistent. What we  
actually want is (1), though.

>    Or this would get you all things in the map
>
>       // tm:subject

"Things" isn't very concrete, is it? :)

>    Structured Discussion
>    ---------------------
>
>       ? Should all map items be an instance of tm:subject implicitly
>         + tm:subject is a great placeholder
>         - TMDM does not say it (or does it?)

Whooops. Does this mean that you intend for it to be (2)?

>       ? Should all topics be a subclass of tm:subject implicitly
>         + tm:subject is a great placeholder
>         - TMDM does not say it (or does it?)

Here it's (1), right?

And, no, TMDM does *not* say this. The prose implies it, but there is  
*no* formal machinery that does anything like this.

--Lars M.