W3C home > Mailing lists > Public > semantic-web@w3.org > November 2012

Re: rdf semantics and timelessly true

From: Nathan <nathan@webr3.org>
Date: Wed, 14 Nov 2012 16:42:41 +0000
Message-ID: <50A3CA01.2080400@webr3.org>
To: Pat Hayes <phayes@ihmc.us>
CC: Sergey Larionov <s.larionov@rks.karelia.ru>, Semantic Web <semantic-web@w3.org>
Pat Hayes wrote:
> 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. 

What about any data that changes? if <http://webr3.org/nathan#me> refers 
to "me", and I change my name from Nathan to Bob, then I cannot update 
my RDF to reflect this? or perhaps more realistically, my email address?
Received on Wednesday, 14 November 2012 16:51:26 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 21:45:52 GMT