W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > October 2002

Re: possible untidy route

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Fri, 11 Oct 2002 14:55:23 +0100
Message-Id: <5.1.0.14.2.20021011145313.03ac7dc0@127.0.0.1>
To: pat hayes <phayes@ai.uwf.edu>
Cc: w3c-rdfcore-wg@w3.org

At 12:38 PM 10/9/02 +0100, pat hayes wrote:

>I hesitate to tread into this yet again lest I fall through the crust, but 
>heres an idea which might just keep everyone happy. It is a variant on the 
>old idea of semantically untidy literals, but it still supports the 
>critical tidy-style entailment.

OK, I'll bite...

You give us:

   Jenny ex:age '10' .
   ex:movie ex:title '10' .
entails
   Jenny ex:age _:x .
   ex:movie ex:title _:x .

But does:

   Jenny ex:age '10' .
   ex:age <datatyperange> xsd:integer .
   ex:movie ex:title '10' .
   ex:title <datatyperange> xsd:string .
entail
   Jenny ex:age _:x .
   ex:movie ex:title _:x .
?

If no, then this is non-monotonic.

If yes, what is this value _:x that is in some sense both an integer and a 
string?

#g
--

>In our test-case style, here are the entailments you would get.
>
>Jenny ex:age '10' .
>ex:movie ex:title '10' .
>
>entail
>
>Jenny ex:age _:x .
>ex:movie ex:title _:x .
>
>BUT if you also say (ignore syntactic details)
>
>ex:age dtyperange xsd:integer .
>ex:title dtyperange xsd:string .
>
>then that is OK, and now you can infer
>
>Jenny ex:age _:y .
>_:y xsd:integer '10' .
>
>ex:movie ex:title _:z .
>_:z xsd:string '10' .
>
>Obviously _:y isn't the same as _:z. The cost is, that _:x isn't the same 
>as either of them. In fact, _:x can't be a datatype value for *any* 
>datatype. Think of it as a kind of generic exemplar for the set of all the 
>possible datatype values, or something like that. Still, it *exists*.
>
>This could work with lexically tidy literals, but it would be classed as 
>semantically untidy, I guess. But it would be easy to tweak the MT to 
>allow this.
>
>Any takers? Questions?
>
>Pat
>
>
>--
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-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Friday, 11 October 2002 09:30:31 EDT

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