[topicmapmail] LTM 1.3 Change Proposal

[Murray Altheim]

Resending to the list a message I accidentally just sent to Lars Marius:

-------- Original Message --------
Subject: Re: [topicmapmail] LTM 1.3 Change Proposal
Date: Mon, 20 Dec 2004 22:04:46 +0000
From: Murray Altheim <m.altheim@open.ac.uk>
Organization: Knowledge Media Institute
To: Lars Marius Garshol <larsga@ontopia.net>
References: <m3r7lovqje.fsf@pavarotti.intern.opera.no> <41C33678.3060401@open.ac.uk> 
<5E3D594E-50ED-11D9-B667-000A95F0602C@deri.org> <41C429BE.2030401@open.ac.uk> <m3wtvc1wrl.fsf@ontopia.net>

Lars Marius Garshol wrote:
> * Murray Altheim
> |
> | The '<' character is XML markup, and I think Lars Marius has been
> | wise to avoid using characters that would make it difficult to embed
> | LTM in XML, XHTML or HTML documents.
> 
> The '<' character does seem more intuitively appropriate for this
> function, but as you point out there are serious problems with it.
> (That '<' is currently not used in LTM is in large part thanks to you,
> though.)

I'm not sure if that's a good thing or a bad thing, but for my own
purposes I'm glad LTM remains "XML friendly." I like the mnemonic
of '<' as much as anyone, but OTOH it is actually a bit confusing
since directedness is not visualized consistently by everyone, and
this prejudices the visualization (i.e., the arrows can point either
way in a visualization, depending on who you talk to -- it's just
an aesthetic thing and there really isn't any standard).

> | I note that Kal has developed some additional PSIs for type
> | hierarchies that have a more specific definition than the one in XTM
> | 1.0, [...]
> 
> If you mean the hierarchical-association-type PSI that is actually
> less specific than the xtm:superclass-subclass PSI, and also on a
> different level, since it's a type of association type. (In fact,
> xtm:superclass-subclass is an instance of
> kal:hierarchical-association-type.)

Yes, of course, you are correct. I was not being very precise.

> | but for my purposes and requirements I kinda prefer both the
> | ubiquity of using XTM's existing association, and frankly am not so
> | concerned with the logical precision of the difference. 
> 
> The difference is *big* (assuming we are talking about the same PSI),
> but even so I think you've made the right choice.

Well, as I've gotten further along in my own research I've realized
that a lot of the precision people claim about their projects,
products and specifications is illusory, even as it is specified,
much less as it is used. Looking back on XTM 1.0 PSI set I thought
(out of ignorance) we were being pretty canonical, but now I realize
we were simply defining one set of possible semantics from among the
many possible, and absent a truly mathematical definition, it was all
just prose. That doesn't buy anything with mathematicians. Our audience
wasn't mathematicians, though I was happy to see that paper describing
XTM in formal logical terms. Can't seem to find a reference to that
now...

I agree though that the difference is big. Earlier this year I'd
started a discussion with Bernard about creating a PSI set for
an order relation. I'm currently using one in Ceryle to set the
direction of ordered relations (as visualized in the graph), but
I'm in no way satisfied with the prose of my definitions. At some
point when Bernard and I have some time, and if you or anyone else
is interested, it'd be good to at least have a public PSI somewhere
for ordered relations. At some point for all of FOL. John Sowa has
quite a lot of stuff defined in his Knowledge Representation book,
and Cyc is a good source too. I prefer not to have to define anything
myself if somebody with more expertise and experience has already
done so...

Murray  (now completely full of fried chicken)

......................................................................
Murray Altheim                    http://kmi.open.ac.uk/people/murray/
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK               .

                  Empty handed, holding a hoe,
                  Walking, riding a water buffalo,
                  A man is crossing over a bridge;
                  The bridge, not the water, flows.

                         -- Mahasattva Fu, The Blue Cliff Record [96]