[sc34wg3] Semantics of subject, topic type, etc

Murray Altheim murray06 at altheim.com
Thu Jun 1 18:46:32 EDT 2006

Quoting Lars Marius Garshol <larsga at ontopia.net>:
> * Murray Altheim
>> I realize you weren't there for the XTM 1.0 discussions, but
>> we very deliberately decided to create PSIs for all Topic Map
>> constructs that we wanted to be able to distinctly reify, and
>> no more than that.
> Well. XTM 1.0 does not specify what can be reified. It hints that this
> is only topic characteristics, but that's clearly not what was actually
> intended, and even if it was it would be at odds with what core.xtm
> defines PSIs for.

You seem quite comfortable to make assumptions about the intentions
of the XTM standard, though you are wrong.  This is not at odds with
core.xtm; we designed it specifically to permit reification following
specific discussions about whether or not to put IDs on things in order
to do so. We did not specify the limits of what can be reified because
this would have limited application, and at the time we did not know
the limits of applicability. We still don't. We decided on a liberal
approach to permit IDs on anything because there could be applications
that required it, and we were not in a position to be a police force.

For example, there would seem to be no need to reify a <mergeMap>
element, but Topic Map editors might still need to uniquely identify
it, and there *might* be applications that had a proper requirement
for Topic Map reification -- who knows? Things have since then worked
without any problems so far as I know, despite your opinion. There is
functional software built upon the XTM 1.0 Specification that uses
core.xtm, and I've seen none that suggests any mismatch between the
existing usage and any purported intention. I don't see how you can
make statements that seem so clearly at odds with reality.

> In any case, you are referring to the state of Topic Maps
> standardization as it was in late 2000. Today what can and
> cannot be reified is defined by TMDM.

No, the standard from 2000 is still a functional ISO standard and
there is still a growing body of people using it. The TMDM defines
what it likes. There will be many people who will ignore the TMDM,
particularly those who have an investment in XTM and don't want to
retool to match what is a new and different Topic Map standard.
This is always the danger inherent in making substantial changes
to an existing standard.

>> As for formal semantics, I don't see that your blog entry is any
>> more formal than the prose text of the XTM 1.0 prose text. [...]
> I don't think I want to enter into a discussion about whether we can
> call this formal semantics or not.

I'm not interested in entering into a discussion either, which would
be pointless. I'm just suggesting that you not call something formal
if you're not defining it formally. As a term of art it is well known
(though more commonly called a "model-theoretic semantics") and has
been used for much longer than either of us has been alive. The ISO
specification either includes a formal, mathematical definition or it
does not; this isn't really a topic of discussion. From what I've
seen this can demonstrably be shown to not be the case. There is
therefore no further discussion necessary.


Murray Altheim <murray06 at altheim.com>                              ===  = =
http://www.altheim.com/murray/                                     = =  ===
SGML Grease Monkey, Banjo Player, Wantanabe Zen Monk               = =  = =

       In the evening
       The rice leaves in the garden
       Rustle in the autumn wind
       That blows through my reed hut.  -- Minamoto no Tsunenobu

More information about the sc34wg3 mailing list