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Re: Inferring that a Camera is a SLR?

From: Richard H. McCullough <rhm@cdepot.net>
Date: Fri, 18 Apr 2003 21:24:02 -0700
Message-ID: <001f01c3062b$a831eb30$bd7ba8c0@rhm8200>
To: "David Jacobs" <djacobs@mitre.org>, "Roger L. Costello" <costello@mitre.org>
Cc: <www-rdf-interest@w3.org>

FYI
The MKR version of David's definition is

    SLR isa Camera with viewFinder = ThroughTheLens;

============ 
Dick McCullough 
knowledge := man do identify od existent done; 
knowledge haspart proposition list; 

----- Original Message ----- 
From: "David Jacobs" <djacobs@mitre.org>
To: "Roger L. Costello" <costello@mitre.org>
Cc: <www-rdf-interest@w3.org>
Sent: Friday, April 18, 2003 11:49 AM
Subject: Re: Inferring that a Camera is a SLR?


> 
> Roger,
> 
> To get the inference you want you would need to assert that all Cameras 
> with through the lens viewfinders are SLRs (which is not true 
> obviously).  But if you wanted to make that assertion you could define 
> the SLR class as:
> 
> <owl:Class rdf:ID="SLR">
>   <owl:intersectionOf rdf:parsetype="Collection">
>     <owl:Class rdf:about="#Camera">
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="#viewFinder"/>
>       <owl:hasValue rdf:resource="#ThroughTheLens"/>
>     </owl:Restriction>
>   </owl:intersectionOf>
> </owl:Class>
> 
> With this definition you could make the inference you wanted.
> 
> Cheers,
> David
> 
> Roger L. Costello wrote:
> 
> >Hi Folks,
> >
> >I am a bit stuck on an inference.  I want to be able to infer that this
> >document is talking about a SLR:
> >
> ><Camera>
> >     <viewFinder rdf:resource="http://www.camera.org#ThroughTheLens"/>
> >     ...
> ></Camera>
> >
> >Here is the piece of knowledge that I am trying to use to make the
> >inference: 
> >
> >    "Only SLRs have a ThroughTheLens viewFinder"
> >
> >When I defined SLR I restricted the value of viewFinder to
> >'ThroughTheLens', as shown here:
> >
> >     <owl:Class rdf:ID="SLR">
> >          <rdfs:subClassOf rdf:resource="#Camera"/>
> >          <rdfs:subClassOf>
> >              <owl:Restriction>
> >                   <owl:onProperty rdf:resource="#viewFinder"/>
> >                   <owl:hasValue rdf:resource="#ThroughTheLens"/>
> >              </owl:Restriction>
> >          </rdfs:subClassOf>
> >     </owl:Class>
> >
> >And when I defined viewFinder I stated that it is a FunctionalProperty
> >and all Cameras have a viewFinder:
> >
> >     <owl:ObjectProperty rdf:ID="viewFinder">
> >          <rdf:type rdf:resource="&owl;#FunctionalProperty"/>
> >          <rdfs:domain rdf:resource="#Camera"/>
> >          <rdfs:range rdf:resource="#Viewer"/>
> >     </owl:ObjectProperty>
> >
> >Initially, I thought that these two OWL statements were sufficient to
> >allow me to infer for the above instance that the Camera is a SLR.  I
> >now believe, however, that it only allows me to infer that it "may" be a
> >SLR.  True?  What do I need to allow me to infer that the Camera "must"
> >be a SLR?  /Roger
Received on Saturday, 19 April 2003 00:25:09 GMT

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