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Re: homonym URIs (Re: What if an URI also is a URL)

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Thu, 14 Jun 2007 11:24:15 +0200
Message-ID: <4671093F.3070908@mondeca.com>
To: Pat Hayes <phayes@ihmc.us>
Cc: Richard Cyganiak <richard@cyganiak.de>, semantic-web@w3.org

>> Here are two web pages about me:
>>    <http://richard.cyganiak.de/>
>>    <http://ontoworld.org/wiki/Richard_Cyganiak>
>> One is in German, the other in English:
>>    <http://richard.cyganiak.de/> dc:language "de" .
>>    <http://ontoworld.org/wiki/Richard_Cyganiak> dc:language "en" .
>> You say it's OK to use a web page URL to denote the person it's 
>> about, so:
>>    <http://richard.cyganiak.de/> a foaf:Person .
>>    <http://ontoworld.org/wiki/Richard_Cyganiak> a foaf:Person .
>> Both clearly denote the same person, so we can confidently state:
>>    <http://richard.cyganiak.de/>
>>       owl:sameAs <http://ontoworld.org/wiki/Richard_Cyganiak> .
> Ah, no. You can't do that so, er, confidently. After all, you are 
> punning, using the same URI to denote several things, so you should 
> only say they are equal in this strong sense when they are equal in 
> ALL their uses. And of course they aren't: they denote different web 
> pages.
If I follow you (and I generally do on those issues, even if it gives me 
hard time), using owl:sameAs this way is always meaning much more than 
the assertion's author generally thinks.
So you agree with the point I made in the Linking Open Data forum that 
e.g   http://dbpedia.org/resource/Berlin owl:sameAs 
is exactly the same case, and we should not have done that, right? I 
hope Richard will get the point from you better than from me. :-)
>> This allows us to conclude:
>>    <http://richard.cyganiak.de/> dc:language "de" .
>>    <http://richard.cyganiak.de/> dc:language "en" .
>> Which is obviously wrong. So what did I do?
> You overused owl:sameAs. 
Repeat after me, Richard : you/we/they OVERUSE owl:sameAs :-)
> Logical equality has to be used with care when punning, its true. This 
> is why OWL 1.1 will (at the time of writing) have three distinct 
> equalities,
Good news, but could you expand on this, and/or provide pointers to the 
OWL 1.1 document(s) defining those three different equalities?
> and why the CL semantics uses true semantic overloading rather than 
> punning, speaking strictly.
> BTW, I opposed including owl:sameAs, i.e. simple equality, into OWL 
> for exactly this reason. But I was overruled :-)
Too bad indeed.
> But you have made a very nice case, which nobody has made to me before.
Well, I thought I'd made a similar one two days ago with the GeoNames / 
DBpedia case at [1]
... but you seem to have missed it. This thread is tricky to follow :-)




*Bernard Vatant
*Knowledge Engineering
*3, citÚ Nollez 75018 Paris France
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Mail:     bernard.vatant@mondeca.com <mailto:bernard.vatant@mondeca.com>
Blog:    Lešons de Choses <http://mondeca.wordpress.com/>
Received on Thursday, 14 June 2007 09:24:24 UTC

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