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Re: RDF triple assertions live forever?

From: Pierre-Antoine Champin <swlists-040405@champin.net>
Date: Fri, 28 Mar 2008 17:59:17 +0100
Message-ID: <47ED23E5.6080908@champin.net>
To: Alan Ruttenberg <alanruttenberg@gmail.com>
Cc: Olivier Rossel <olivier.rossel@gmail.com>, semantic-web@w3.org

Alan Ruttenberg a écrit :
> 
> A hack it is, because the reifications have no semantic implications for 
> the original triple according to the RDF semantics.

anyway, RDF semantics has no immediate support for temporality (i.e. a 
triple is valid at some point in time, invalid at another).

so if you want to reason with this kind of things, it *has* to be some 
kind of meta-reasoning "above" classical RDF reasoning.

of course, you can decide to use RDF to do that meta-reasoning, and this 
is where reification comes handy (to distinguish, in the "meta" layer, 
meta-statements from "lower" statements).

so in my point of view, this is not a hack -- not in the negative sense 
you seem to imply, anyway ;)

   pa


> -Alan
> 
> On Mar 28, 2008, at 6:36 AM, Olivier Rossel wrote:
> 
>>
>> you can hack conditional statements in RDF with reification.
>> cf http://lists.w3.org/Archives/Public/semantic-web/2008Mar/0085.html
>>
>> On Fri, Mar 28, 2008 at 10:58 AM, Phil Archer <parcher@icra.org> wrote:
>>>
>>>  Being the one who kicked this off by making the original assertion
>>>  (which I actually got from someone else but almost certainly
>>>  mis-interpreted along the way) I feel I should give a little further 
>>> input.
>>>
>>>  Actually, it's _good news_ (as well as common sense) that triples don't
>>>  get stored in perpetuity. I came to this from the standpoint of wanting
>>>  to make the statement (in a semantic way) that
>>>
>>>  foaf:Agent "will stand by the following assertions until" $date
>>>
>>>  Which is a little different from a cache header...
>>>
>>>  Phil.
>>>
>>>
>>>
>>>  Renato Golin wrote:
>>>>
>>>> Phillip Rhodes wrote:
>>>>> In a discussion that has arisen recently on the foaf-dev list, 
>>>>> somebody
>>>>> pointed out that they've been told that RDF triples live forever.
>>>>> That is, once something is asserted it is considered asserted until,
>>>>> as it
>>>>> was put, "the entropic heat death of the universe."
>>>>
>>>> Hi Phillip,
>>>>
>>>> This assertion is, to me, the same as to say all web pages are static,
>>>> meaning that you can cache them locally without any further attempt to
>>>> get it back from the server again.
>>>>
>>>> All web browsers have a fair cache policy which we're all used to
>>>> (Shift-F5 and stuff) so no big deal to do the same with triples and RDF
>>>> browsers.
>>>>
>>>> Also, with RDF is easier to say that site A has "the same triple as"
>>>> another site B but with different content, who will you trust? Let's 
>>>> say
>>>> you have a timestamp annotating the triples, would you still believe 
>>>> the
>>>> "newest" one?
>>>>
>>>> Site A:
>>>>   renato is bad (today)
>>>>
>>>> Site B:
>>>>   renato is good (10 years ago)
>>>>
>>>> It's the same with RDFAuth, you have to trust someone sometime, you 
>>>> need
>>>> a list of trusted sites, people, documents, beliefs. If your site says
>>>> "renato is bad" it may "like" better Site A and even automatically add
>>>> it to the "trusted sites" or even keep a score of things you agree with
>>>> the site as the "automatic trust level" as opposed to your "hardcoded
>>>> trust level" when you trust someone even if you don't agree with 
>>>> him/her.
>>>>
>>>> The possibilities are endless...
>>>>
>>>> cheers,
>>>> --renato
>>>>
>>>>
>>>>
>>>
>>>  --
>>>  Phil Archer
>>>  Chief Technical Officer,
>>>  Family Online Safety Institute
>>>  w. http://www.fosi.org/people/philarcher/
>>>
>>>
>>>
>>>
>>>
>>
> 
> 
Received on Friday, 28 March 2008 17:00:12 UTC

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