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Re: class and inviduals

From: Pavel Klinov <pklinov@cs.man.ac.uk>
Date: Tue, 16 Nov 2010 16:50:57 +0000
Message-ID: <AANLkTinyPNPrGTn74kG-d94Aey53aiAX=AW_e4OHXGkL@mail.gmail.com>
To: Pat Hayes <phayes@ihmc.us>
Cc: Marco Colombetti <colombet@elet.polimi.it>, public-owl-dev@w3.org
Are we still talking about punning in OWL 2 or whether some KR&R
formalism should explicitly separate individual names from other
things (e.g. predicate names)? These seem like two very different
questions to me.

As for OWL 2, I do agree with Enrico. Punning is a not quite a logical
pattern - it's a meta-modeling feature and has to be used with care.
If you pun an object X and a class X they will still be treated as
separate entities by a reasoner ("X-as-class" and "X-as-individual" if
you will). It can be confusing, for example, one may place a data
property assertion on X (as an individual) and then wonder why other
instances of X (as a subclass) do not inherit that property. At the
same time other tools, like Protege, may give a false impression that
"these are really the same thing".

Apologies if I'm mistaken in my understanding of punning.

Cheers,
Pavel

On Tue, Nov 16, 2010 at 3:08 PM, Pat Hayes <phayes@ihmc.us> wrote:
>
> On Nov 16, 2010, at 4:22 AM, Marco Colombetti wrote:
>
>> Aldo is right, punning is allowed in OOWL2, but I wonder whether it should be considered as good practice. In my opinion it conceils certain important modelling choices, and is likely to induce confusion.
>>
>> Any strong opinion about this?
>
> Yes, one strong opinion: it is VERY good practice. The ISO Common Logic framework goes slightly further, allowing any 'thing' to be treated simultaneously as an individual, a class or a relation ('property') of any number of arguments; and we have found in many applications that the resulting freedom to express ontological decisions independently from the apparent constraints of the logic is more than 'good' : it represents a quantum jump in ontology engineering.
>
> The key point is that 'individual' in a metaphysical sense is one notion, whose merits can be debated; but 'individual' in the logical sense is quite another. The latter means simply 'a member of the universe of discourse' or 'within the scope of quantification'. The traditional 'good practices' typically get these two distinct notions confused, and use syntactic constraints arising from the latter to model the former, to the lasting detriment of good ontological engineering.
>
> Pat Hayes
>
>>
>> Marco
>>
--pavel
http://www.cs.man.ac.uk/~klinovp
Received on Tuesday, 16 November 2010 16:51:36 GMT

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