# Re: Even more Fuzzy about FunctionalProperty!

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 05 Mar 2003 09:24:00 -0500 (EST)
Message-Id: <20030305.092400.63242793.pfps@research.bell-labs.com>

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From: "Roger L. Costello" <costello@mitre.org>
Subject: Re: Even more Fuzzy about FunctionalProperty!
Date: Wed, 05 Mar 2003 08:33:28 -0500

>
> Thanks Mike.  I am not real comfortable that you have completely
> answered my question, so let me followup with the example that you
> presented.
>
> You have stated that "hasFather" is a FunctionalProperty.  Consider
> these two instances:
>
> <Person rdf:ID="Mike">
>     <hasFather>
>         <Person rdf:ID="Joe">
>             <age>56</age>
>         </Person>
>     </hasFather>
> </Person>
>
> <Person rdf:ID="Mike">
>     <hasFather>
>         <Person rdf:ID="Joseph">
>         </Person>
>     </hasFather>
> </Person>
>
> Since "hasFather" has been declared to be a FunctionalProperty can we
> infer that this:
>
>         <Person rdf:ID="Joe">
>             <age>56</age>
>         </Person>
>
> is equivalent to this:
>
>         <Person rdf:ID="Joseph">
>         </Person>

From the premise you gave, you can infer

<Person rdf:ID="Joe">
<owl:sameIndividualAs rdf:resource="Joseph" />
</Person>

you can also infer

<Person rdf:ID="Joseph">
<age>56</age>
</Person>

and lots of other things.

> Thus, when inferencing do we treat the values of "hasFather" as a "black
> box", or must we "reconcile" the values?  /Roger

No.  OWL has no notion of objects as black boxes, nor is such a notion
needed in OWL.  Neither does OWL have a notion of reconcilliation, nor is
such a notion needed in OWL.  It is true that an OWL will be able to infer
that Joe and Joseph denote the same individual, and thus that everything