[topicmapmail] LTM 1.3 Change Proposal

[Steve Pepper]

* Lars Marius:

| We've now decided to try to do LTM 1.3 as soon as possible, and to
| this end I've updated the change proposal to reflect our latest
| thoughts on this.
| 
| It can be found at
| 
| <URL: http://www.ontopia.net/topicmaps/materials/ltm-1.3-prop-2.html >


My comments are as follows. (I would particularly like to
hear feedback on my suggestion for reification.)


1. Introduction
...............

| if all of these changes are accepted for LTM 1.3 it
| will be no less expressive than XTM 1.0.

Not quite:

* variant names with <resourceRef>
* reification of association roles (at least acc. to proposal)
* untyped associations and occurrences
* untyped association roles

We need to decide whether it is a goal for LTM (or LTM 1.3)
to express everything that can be expressed in XTM. My feeling
is that it should be... but that it should also be a goal to
keep the syntax as simple as possible.

Another goal, I think, should be to avoid multiple ways to
express the same thing (even though this might otherwise have
made the notation more compact).

We also need to consider the impact of XTM 1.1:

* typed basenames
* embedded XML
* ... (?)


2. The #INCLUDE directive
.........................

Yes.


3. The #VERSION directive
.........................

Yes.


4. URI prefixes
...............

Yes with comment:

Suggest #PREFIX instead of #URIPREFIX. Rationale:

* No point in making it more verbose than necessary
* The term "prefix" is sufficiently clear
* N3 has @prefix for exactly the same thing


5. Reification support
......................

I would like to see this kept as simple and clean as possible.

Would it be possible to have a single convention for every
form of reification, including names, roles and topic maps?

For some reason I find it very natural to use "@" as the
delimiter for reification, even though (or perhaps BECAUSE)
it is already used for subject indicators. (After all,
reification involves regarding the syntactic construct as the
subject identifier for the topic map construct that is being
reified.)

Would allowing

   "@" NAME

after a name, association, role, or occurrence (or preceding
any of the above, in the case of the topic map) be sufficiently
clear and unambiguous, I wonder. Lars Marius' examples in
[1] would then read as follows:

  [ltm : syntax = "LTM" / acronym @ltm-name]

  invented-by(ltm-name-topic : invention, steve-pepper : inventor) @invented

  {ltm, specification, "http://www.ontopia.net/download/ltm.html"} @ltmspec

Roles would be handled as follows:

  invented-by(ltm-name-topic : invention @ltm-invention,
              steve-pepper : inventor @ltm-inventor)

Reifying the topic map would simply be as follows:

  @tm-topic  /* preceding any topics, occurrences or associations */

The only possibly confusing scenario would be when reifying a name
and at the same time specifying a subject identifier for the topic
to which the topic belongs:

  [ltm : syntax = "LTM" / acronym @ltm-name
    @"http://psi.ontopia.net/topicmaps/LTM"]

However, the distinction between

  @ NAME

and

  @ uri

(where 'uri' is a quote-delimited string) is sufficient to prevent
ambiguity, is it not?


6. Variant names
................

I'm not sure I fully understand this proposal. Perhaps Lars Marius,
could provide a description such as would go into the User's Guide
to LTM. (If the proposal can't be described in simpler terms, then
that in itself is a problem.) I'll comment on the proposal once I've
seen the new description.

Best regards,

Steve

--
Steve Pepper <pepper@ontopia.net>
Chief Strategy Officer, Ontopia
Convenor, ISO/IEC JTC 1/SC 34/WG 3
Editor, XTM (XML Topic Maps 1.0)