Re: class and inviduals

On 16 Nov 2010, at 16:19, Aldo Gangemi wrote:

> Fully agree with Pat: let's stop confusing metaphysics with logic :)

Indeed: OWL is a classical logical formalism, with a syntax and a semantics, and you have to buy its consequences. Yes, I agree with Pat when he says "'individual' in the logical sense means simply 'a member of the universe of discourse' or 'within the scope of quantification'". Therefore using the same label for an individual, a concept or a relation in a logic with punning doesn't quite buys you the consequence you may expect from a truly higher order logic; so, usually I discourage this practice for KR. I suggest to (re)read the very well written paper [1].
cheers
--e.

[1] Boris Motik: On the Properties of Metamodeling in OWL. J. Log. Comput. 17(4): 617-637 (2007)
<http://www.comlab.ox.ac.uk/boris.motik/pubs/motik07metamodeling-journal.pdf>

> 
> I add that we need to distinguish punning as a good logical pattern versus any design pattern that can help clarifying if it is the case (and how) to use it for some domain, e.g. to model car companies and car models, car models and concrete cars, product type and product instances, classes and topics, etc. Cf. [1] for a growing repository of patterns.
> 
> Best
> Aldo
> 
> [1] http://www.ontologydesignpatterns.org
> 
> On 16 Nov 2010, at 16:08, Pat Hayes 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
>>> 
>>> 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
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> 
> 
> 
> _____________________________________
> 
> 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
>