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Re: class and inviduals

From: Enrico Franconi <franconi@inf.unibz.it>
Date: Tue, 16 Nov 2010 13:26:30 +0100
Cc: public-owl-dev@w3.org
Message-Id: <E5C52CC2-3C70-4265-90B4-A674A7EE05D0@inf.unibz.it>
To: Marco Colombetti <colombet@elet.polimi.it>
On 16 Nov 2010, at 11:22, 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?

Mine :-)
Properties you may attach to the individual do not interact with the properties you may attach to the concept: indeed, the fact that the concept and the individual have the same name is purely accidental and it will not be exploited by the reasoner. To my opinion, punning is good for annotations, and generally it should be avoided to encode knowledge.
On the other hand, a good domain and usage analysis is required to understand whether something is going to be a concept or an individual. It is the VERY SAME thing as designing an information system (such as, e.g.,  a relational database): depending on the domain and the usage, a real world entity may end up to be a relation, an attribute, or a value, and the methodologies to understand that are well known in any DB design book.

> On Mon, 15 Nov 2010 23:50:43 +0100
> Aldo Gangemi <aldo.gangemi@cnr.it> wrote:
>> Hi Marcel, this is a typical modelling issue. The solution is to treat terms alternatively as classes or individuals according to the requirement (or conceptualization) you have. In case you want to talk of Ferrari as a company, and your requirement is e.g. to ask about the foundation date of a company, Ferrari should be an individual; if you want to talk about Ferrari as a class of all concrete cars produced by Ferrari-the-company, you probably want to model Ferrari as a class.
>> In case of strong ambiguity, e.g. with maximally specified car models such as "Ferrari 365 GT/4 BB" (either a model or a concrete example of that model), OWL2 is very good at modelling the ambiguity by means of the so-called "punning" mechanism: the same term holds two different interpretations.
>> Good luck
>> Aldo On 15 Nov 2010, at 22:59, Marcel Ferrante wrote:
>>> Hi,
>>> Sometimes, when we define class and individual to students, appears some doubts.
>>> For example:
>>> In the owl reference (http://www.w3.org/TR/owl-ref/) class is defined as "abstraction mechanism for grouping resources with similar characteristics"
>>> or class define a set of individuals with same characteristics in common.
>>> A good exemple is car (class) and ferrari enzo (individual).
>>> But there is many cars that are ferrari enzo, so ferrari enzo could be a class and Jonh's ferrari enzo an individual.
>>> So ferrari enzo could be a class and an invidividual in the same ontology ? Or ferrari enzo could be a subclass of car,
>>> but its diferent than a tradiconal subclass like sport car.
>>> Is there a more clear definition of class and individual ?
>>> Thanks in advance,
>>> Marcel
>>> -- 
>>> Marcel Ferrante Silva
>>> +55 31 8851-9069 3785-9069
>>> skype: marcelferrante
>>> gtalk: marcelf@gmail.com
>> _____________________________________
>> Aldo Gangemi
>> Senior Researcher
>> Semantic Technology Lab (STLab)
>> Institute for Cognitive Science and Technology,
>> National Research Council (ISTC-CNR) Via Nomentana 56, 00161, Roma, Italy Tel: +390644161535
>> Fax: +390644161513
>> aldo.gangemi@cnr.it
>> http://www.stlab.istc.cnr.it
>> http://www.istc.cnr.it/createhtml.php?nbr=71
>> skype aldogangemi
>> okkam ID: http://www.okkam.org/entity/ok200707031186131660596
Received on Tuesday, 16 November 2010 12:27:05 UTC

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