Lars Marius Garshol
larsga at garshol.priv.no
Mon Nov 5 04:34:53 EST 2007
* Patrick Durusau
> I assume that the only inferencing that we are concerned with is
> that of supertype-subtype?
Not necessarily. There is subtyping of topics, subtyping of
statements, and then there is the issue of what is implied by scope,
etc. I think we agreed to limit ourselves to the two kinds of
subtyping in Leipzig.
A full formal semantics would require more than that, though.
> Since it is transitive it is possible to have relationships that
> are not explicitly represented in the topic map.
Correct. And the same thing is in principle what happens in all the
other cases, too.
> Which means that a processor the supports inferencing will have to
> deal with loops. (TMDM 7.3, Note 1)
> And, "...should be interpreted that the sets of all instances for
> all types in the loop are the same."
> I am having trouble with that part of Note 1. Does it mean that all
> the instances are instances of all the types, even though the note
> goes on to say that does not imply that the types are the same?
For all t where t is a type in the loop, the query
$i isa t
will produce exactly the same result. However, the t's will actually
be different topics.
Does that clarify it?
> In other words, if there is a loop, I could infer that some
> instance is an instance of multiple types?
> I don't have any suggestions but just wanted to make sure I was
> understanding the issue properly.
Well, this is not the issue. This is not an issue at all, actually. :-)
The real issue is, let's say we have the following topic map (in CTM):
a isa b .
b ako c .
If I now do a query to count all the associations that 'a' has, is
the answer going to be 1 (a isa b) or 2 (a isa b, a isa c)?
I've added this explanation to the issue now, in the hope that this
makes things clearer.
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