W3C home > Mailing lists > Public > semantic-web@w3.org > August 2008

Re: Why do you want to do that?

From: Denny Vrandečić <dvr@aifb.uni-karlsruhe.de>
Date: Tue, 12 Aug 2008 16:48:53 +0200
Message-ID: <48A1A2D5.90708@aifb.uni-karlsruhe.de>
To: "Richard H. McCullough" <rhm@pioneerca.com>
CC: Pat Hayes <phayes@ihmc.us>, Semantic Web at W3C <semantic-web@w3.org>, KR-language <KR-language@YahooGroups.com>

Richard H. McCullough wrote:
> ----- Original Message ----- From: "Denny Vrandečić"
>> Another example: why cannot Eagle be both a class (for "Fred the eagle")
>> and an individual (instantiating the class "species")? (similar to
>> Boris' example from his paper)
> It can, but my point is that these are two different
> word-senses/meanings/definitions
> which are defined in two different contexts.  They are "view"ed as
> different things
> in these two different contexts.
>    at view = class { Fred the eagle isu Eagle; };
>    at view = individual { Eagle isu species; };     # Aside:  I would
> treat this "Eagle" as a subClass, not an Individual:  Eagle iss species;

I disagree here with your aside: Eagle is not a subclass of species, but
a subclass of animal. Eagle is indeed an instance of species. I assume
that subclassing means that every instance of a subclass is also an
instance of the superclass, which, in the case that Eagle would be a
subclass of species would mean that Fred the Eagle is also a species. Or
does your definition of subclass also differ (which would be fine, but
important to know)?

> When you mix the contexts together
>    at view = mix { Fred the eagle isu Eagle; Eagle isu species; };
> the meaning of "Eagle" in the first statement is different from
> the meaning of "Eagle" in the second statement.
> "Eagle" is a name which refers to two different concepts, which
> we might designate as Eagle_class and Eagle_individual.
> Declaring that "Eagle" is a Class and an Individual only compounds
> the confusion.

Yes, I understand your position, and I agree that it is indeed a
reasonable and possible position -- as said, OWL DL, e.g. takes it, and
you say Ayn Rand also supports it :) Nevertheless I personally think
that it is easier to allow to state the equivalence of the class Eagle
and the individual eagle, and that this is actually less confusing for
the normal user. So, for me, I got a deeper understanding of the topic
but still remain with Pat's definitions (as they are in RDF or OWL2).

I guess, we agree to disagree :)

I mean, heck, the normal user hardly understands the difference between
the <strong> and the <b> tag in HTML, and we want him to figure out the
difference between Eagle_class and Eagle_individual?

> 1. I think that my definitions of "individual" and "class" are consistent
> with the description at the beginning of section 3.1.3 of OWL Guide.

OK, this makes sense.

> 2. My ultimate source of definitions is the "unit" and "concept" of
> Ayn Rand (Introduction to Objectivist Epistemology).
> I guess I should "shut up" and refer you to Ayn Rand.
> She has a knack for clear explanations; I do not.

I guess I should read Ayn Rand. Being rather strongly influenced by
constructivist epistemology I am afraid this won't be an easy read for
me and may take a while...

>> And now back to my thesis ...
> What's your thesis topic?

Ontology evaluation :) [1]


Received on Tuesday, 12 August 2008 14:49:31 UTC

This archive was generated by hypermail 2.4.0 : Tuesday, 5 July 2022 08:45:08 UTC