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Re: rdf semantics and timelessly true

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 14 Nov 2012 09:40:25 -0800
Cc: "nathan@webr3.org" <nathan@webr3.org>, Sergey Larionov <s.larionov@rks.karelia.ru>, Semantic Web <semantic-web@w3.org>
Message-Id: <12666691-5ABB-4D00-AAD7-D708DFE6BACE@ihmc.us>
To: Cory Casanave <cory-c@modeldriven.com>

On Nov 14, 2012, at 8:36 AM, Cory Casanave wrote:

> Re: It assumes, implicitly, that URI references have the same meaning whenever they occur."
> 
> That assumption seems to have been overtaken by events, technologies and usage over time. 

Over time, hah.

Possibly, although I know that many users of RDF do in fact use it "properly" in this regard. For sure, there seems to be a conceptual gap between users who think of RDF as timeless and those who see it as a vehicle for time-sensitive information. And as long as this gap exists, mutual incomprehension will occur. I am not sure what we can do about this situation, unfortunately. 

Pat

> 
>> -----Original Message-----
>> From: Pat Hayes [mailto:phayes@ihmc.us]
>> Sent: Wednesday, November 14, 2012 11:27 AM
>> To: nathan@webr3.org
>> Cc: Sergey Larionov; Semantic Web
>> Subject: Re: rdf semantics and timelessly true
>> 
>> 
>> On Nov 14, 2012, at 8:03 AM, Nathan wrote:
>> 
>>> Hi Pat,
>>> 
>>> Pat Hayes wrote:
>>>> Its not impossible, and in a strong sense this is required by the current RDF
>> semantics, which treats all RDF assertions as timelessly true.
>>> 
>>> Can you refine / expand on this please? I'd presumed RDF to have no
>> consideration of time - e.g time-less; as opposed to being true for all time
>> (timeless).
>>> 
>>> TIA,
>>> 
>>> Nathan
>> 
>> Yes, time-less is a better way to put it. But it is so because URIreferences are
>> assumed (and I know this is an idealization, but...) to be timeless in how they
>> refer. Section 1.2 says:  "... the semantics simply assumes that ... a single URI
>> reference can be taken to have the same meaning wherever it occurs. Similarly,
>> the semantics has no special provision for tracking temporal changes. It
>> assumes, implicitly, that URI references have the same meaning whenever they
>> occur."
>> 
>> In other words, no counters allowed.
>> 
>> Pat
>> 
>> 
>>> 
>>> 
>> 
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>> 
>> 
>> 
>> 
>> 
> 
> 
> 

------------------------------------------------------------
IHMC                                     (850)434 8903 or (650)494 3973   
40 South Alcaniz St.           (850)202 4416   office
Pensacola                            (850)202 4440   fax
FL 32502                              (850)291 0667   mobile
phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
Received on Wednesday, 14 November 2012 17:40:59 GMT

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