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Re: [ontolog-forum] Fwd: Ontologies and individuals

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "doug foxvog" <doug@xxxxxxxxxx>
Date: Mon, 17 Dec 2012 12:04:56 -0500
Message-id: <9671ce13a54c272f3ab88ec7d1b6df4e.squirrel@xxxxxxxxxxxxxxxxx>
On Thu, December 13, 2012 11:55, Richard Dapoigny wrote:
> Hi all,
> I see that the debate about identification of individuals is far from
> being consensual.
> However, let us first (try to) agree of some fixed points as we say in
> mathematics.
> A usual definition is to see individuals as entities having no
> instance(s). Is there some agreement about this first definition?    (01)

This definition should be a little stronger (imho) -- to things that
conceptually can have no instances in any possible world.  This is a
feature of the thing being modeled, not of the ontology, context, or
knowledge base.    (02)

"Unicorn" should not be an individual, since there can be instances in a
fantasy world.  Even if the intersection of two classes is empty (e.g.,
"square circle"), that intersection should not be an individual even
though it has no instances.    (03)

I note that according to this definition, relations (if they are
considered to be entities) are individuals, the application of a relation
to a list of arguments, not fitting the definition of "instance" in the
definition of "individual".  If a member of a set is not considered to be
an "instance" of the set, then sets are individuals.  The same argument
applies to "groups" of things -- whose membership can change, unlike sets.    (04)

> This should help to better characterize the link between ontologies and
> individuals.    (05)

I note that OWL-DL distinguishes "classes" and "instances", as being
disjoint.  As such, classes of things (types of wine, animal species,
models of car, ...) are often instances in OWL ontologies.  Of course,
such things can, themselves, have instances -- even though the
impoverished language in which they are represented can not express the
relationship between them and their instances as such.    (06)

Some OWL-DL users use the term "individual" to refer to OWL "instances",
even though those instances (in the real world) have instances of their
own.  These instances can not have their own instances expressed as such
in OWL-DL (although they could be expressed in OWL-FULL).    (07)

> All the best,
> Richard    (08)


> Le 13/12/2012 16:14, Amanda Vizedom a écrit :
>>
>> Hans, et al,
>>
>> Info Systems might not generally make that distinction, but
>> Ontologies, and deployed ontology-based systems can, should, and often
>> do.    (09)

>> The unique name of an individual within an ontology is generally
>> artificial, in order to guarantee uniqueness. Namespaces,
>> Microtheories, and other mechanisms supporting ontology modularity
>> serve to extend that uniqueness beyond the bounds of the original
>> ontology or module.  This is quite separate from any identifier used
>> for the individual in any other system. Best practice IME is to map to
>> identifier systems explicitly, using specific mapping predicates (for
>> example, "socialSecurityNumber," "legalName," "vehicleIdentityNumber,"
>> "serialNumber," "XYZemployeeID"); those predicates can and should
>> themselves be defined with explicit reference to the context in which
>> they apply or authority which issues and uses them. Note, also, that
>> this approach is essentially neutral to metaphysical questions about
>> the individual/class distinction, as identifiers can be, and often
>> are, treated as contextual for any thing in the ontology, and mapping
>> identifiers for classes is often done in precisely the same way, using
>> specific mapping predicates whose context/authority is made explicit
>> (for example, "modelNumber," "cHEBIName," etc.).    (010)

>> This approach also eases things in deployed systems that are used to
>> track (and perhaps eventually unify/identify) initially unidentified
>> things using partial information.    (011)

>> Best,
>> Amanda
>>
>> On Thu, Dec 13, 2012 at 9:42 AM, Hans Polzer <hpolzer@xxxxxxxxxxx
>> <mailto:hpolzer@xxxxxxxxxxx>> wrote:
>>
>>
>>     MW: Identity is different from identifier...
>>
>>     HP: Correct! But information systems generally don't make that
>>     distinction because the only way they have of distinguishing among
>>     individuals is through identifiers -- which have context, usually
>>     implicit and overlooked. And one purpose of the "entity primacy"
>>     principle is to make developers explicitly aware of that
>>     distinction so that they don't mistake the identifiers they are
>>     using for individuals for the identity of those individuals (which
>>     is their own and inherent in their existence in some reality). The
>>     best we can do is to get socio-political agreement on some
>>     "near-innate" identifier for individuals, such as VINS for motor
>>     vehicles intended for use on public roads and MAC addresses for
>>     Ethernet devices. Such identifiers are useful for information
>>     sharing interoperability among diverse contexts about the same
>>     individuals. But we don't really have such an identifier for
>>     people (yet). Maybe some "superDNS" identifier certificate issued
>>     independently of national/local jurisdiction before birth to all
>>     people (like VINs) will be brought about thanks to the Internet,
>>     but I'm not holding my breath. Or maybe some biometric will be
>>     found that can serve as this "near-innate" identifier on the
>>     network. And we need to be vigilant and remember that even these
>>     identifiers are not the same as identity and that the individuals
>>     may have other identifiers in other contexts.
>>
>>
>>
>>
>>
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>
>
> --
> And the wounded skies above say
> it's much too much too late.
> Well, maybe we should all be praying for time.
>
>
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