[sc34wg3] irreflexive isa

[Patrick Durusau]

Greetings!

Some time ago the question of the irreflexive isa was posted as an issue 
with the TMRM.

See: http://www.isotopicmaps.org/pipermail/sc34wg3/2009-April/004141.html

I have responded that I think a broader definition of ins includes the 
more restrictive one of the TMRM, but I also pinged my co-editors for 
their takes on this issue.

Barta responds that the TMDM has the same restrictive definition of isa:

>
> And I see now that TMDM does that too:
>
>    http://www.isotopicmaps.org/sam/sam-model/#sect-types
>
>    A topic type is a subject that captures some commonality in a set
>    of subjects.
>
> According to "normal" set theory, the set is never part of itself. In
> other words, the isa relation between the set and elements of that set
> is always is irreflexive.
>
> And further it strengthens also
>
>    .... A topic type may itself be an instance of another topic type, ....
>
> It does not say
>
>     .... be an instance of any other topic ...
>
> TMDM uses the word ... another ...
>
> So it is fair to assume that irreflexive is intended.
>   
So, if this is an issue with the TMRM, it appears to equally be an issue 
with the TMDM.

Hope everyone is having a great day!

Patrick

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