[sc34wg3] tmrm-map-inferred-information

Patrick Durusau patrick at durusau.net
Mon Nov 5 10:03:33 EST 2007


Lars Marius Garshol wrote:
> * 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."
> Yes.
>> 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?
> Yes.
>> 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.
Thanks! It does make it clearer.

Personally I favor 2 (a isa b, a isa c) because it allows a choice of 
'all' the information or 'only explicit' information. The other option 
seems to unnecessarily restrict topic maps to explicit representation of 

Hope you are at the start of a great week!

> --Lars M.
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Patrick Durusau
patrick at durusau.net
Chair, V1 - US TAG to JTC 1/SC 34
Acting Convener, JTC 1/SC 34/WG 3 (Topic Maps)
Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)
Co-Editor, OpenDocument Format (OASIS, ISO/IEC 26300)

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