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Re: [Welcoming feedback] Semantic Web: Information wants to be useful

From: Steffen Staab <staab@uni-koblenz.de>
Date: Wed, 13 May 2009 09:21:17 +0200
Message-ID: <4A0A74ED.9040702@uni-koblenz.de>
To: Pat Hayes <phayes@ihmc.us>
CC: David Baxter <retxabd@gmail.com>, semantic-web@w3.org
Here is a great account of this problem:

though it is not straightforward to capture this in OWL


Pat Hayes schrieb:
> On May 12, 2009, at 9:06 AM, David Baxter wrote:
>> Pat Hayes said:
>> > I know both Cyc and dbPedia say their
>> > concepts are sameAs one another, but they are both wrong. Cyc defines
>> > a 'piece' of carbon; dbpedia defines the chemical element carbon.
>> > These concepts are NOT owl:sameAs one another, no matter what the
>> > websites say.
>> Hi Pat,
>> We're definitely interested in improving the quality of our owl:sameAs 
>> links to DBpedia and other datasets. In this case, however, I believe 
>> the owl:sameAs link is good -- it's the OpenCyc comment that's bad. 
>> The URI opencyc:Carbon 
>> <http://sw.opencyc.org/concept/Mx4rvVjIQpwpEbGdrcN5Y29ycA> denotes an 
>> owl:Class representing the element carbon. Its instances are 
>> individual pieces of carbon, including diamonds and lumps of coal. 
>> We'll get the comment fixed.
> Hmm. So - just to see if I follow you here - Cyc thinks that a chemical 
> element *is* the class of all its macroscopic pieces? Is this what 
> DBpedia also thinks a chemical element is? Because (a) that seems to me 
> to be a very idiosyncratic view of what a chemical element is, and (b) 
> if DBpedia has some other ontology of chemical-element-hood, then your 
> two concepts are very unlikely to the sameAs one another. Bear in mind 
> that owl:sameAs really does mean logically identity, so ANYTHING said 
> using one name is true using the other. So someone should be able to 
> take any DBpedia content mentioning carbon, and any piece of Cyc content 
> mentioning carbon, substitute one carbon name for the other throughout 
> both chunks, and conjoin them, and the result ought to make sense in 
> both systems. Is that indeed true, in this case? 
> Pat
> PS. What does Cyc do about elements which only exist macroscopically as 
> compounds? If there are no pieces of pure Ytterium, say, then the class 
> Ytterium is the empty class. If there are no pure samples of 
> Einsteinium, similarly. In an OWL reasoner, you could infer that they 
> are the same class, hence sameAs one another (since they are both classes). 
>> David Baxter
>> Cycorp
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Received on Wednesday, 13 May 2009 07:21:52 UTC

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