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Re: RDF* semantics

From: Olaf Hartig <olaf.hartig@liu.se>
Date: Mon, 12 Aug 2019 07:17:42 +0000
To: "public-rdf-star@w3.org" <public-rdf-star@w3.org>
CC: Andy Seaborne <andy@apache.org>
Message-ID: <1565594259.8060.417.camel@lille71.ida.liu.se>
Andy, this sums it up nicely.

Thanks,
Olaf


On Fri, 2019-08-09 at 14:31 +0100, Andy Seaborne wrote:
> Reification can do 3 things: (close by are cases for named graphs)
> 
> 1/ Talk about another triple in the graph - this is edge properties and 
> is RDF* PG mode.
> 
> 2/ Talk about something that isn't asserted or isn't known.
> RDF* SA mode is close to this, I think.
> 
> :moon :color "Green".
> 
>    is not in the graph and
> 
> <<:moon :color "Green">> :saidBy :Bob .
> 
>    is in the graph.
> 
> or
> <<:moon :color "Green">> :claimedFalse :Alice .
> 
> Having both modes does not make sense when graphs are (RDF) merged.
> 
> 3/ Reification can be used for different claims about "the same thing" 
> (a triple with the same appearance).
> 
> <<:moon :color "Green">> :saidBy :Bob ;   :saidOn "Tuesday" .
> <<:moon :color "Green">> :saidBy :Alice ; :saidOn "Monday" .
> 
> This latter case can't be done with a single term for the {:moon :color 
> "Green"} triple - the different properties get mixed up. Yes - better 
> modelling is possible
> 
> <<:moon :color "Green">> :about [ :saidBy :Bob ;   :saidOn "Tuesday" ] .
> <<:moon :color "Green">> :about [ :saidBy :Alice ; :saidOn "Monday"  ] .
> 
> Likewise, clashes happen when two RDF* graphs are merged. (Similar 
> things happen in RDF graphs as well on a lesser and better understood 
> level.)
> 
>      Andy
> 
> On 06/08/2019 16:12, Olaf Hartig wrote:
> > Hi Kingsley,
> > 
> > On Mon, 2019-08-05 at 13:52 -0400, Kingsley Idehen wrote:
> >> [...]
> >> Under what circumstances in the real-world would the condition you model
> >> arise i.e., propositions that don't manifest as part of documentation?
> > 
> > For instance, we my want to capture that Alice told us that Bob's age is
> > 23, even if we don't have a document from Alice with this
> > statement/claim regarding Bob's age.
> > 
> > Another example: we may want to capture that we do not believe that
> > Bob's age is 23, which is independent of whether there exist a document
> > making the claim about Bob's age or not.
> > 
> >> All sentences/statements are inscribed to documents that have provenance
> >> oriented properties such as date, time, author etc..
> >>
> >> What I am trying to articulate here is that its a combination of the
> >> sentence and document (in which they are inscribed) that brings
> >> authority (or lack thereof) to a proposition represented as an RDF
> >> sentence/statement.
> >>
> >> The triple:
> >>
> >> @prefix : <#> .
> >>
> >> :bob foaf:age "23"^^xsd:integer .
> >>
> >> Exists in a document identified by <> , so we a missing the following part
> >> of reality (as I understand it):
> >>
> >> @prefix : <#> .
> >>
> >> <> a foaf:Document .
> >> <> :creator :i .
> >> <> :createdOn "2019-08-05"^^xsd:date .
> >> <> foaf:primaryTopic :bob.
> >>
> >> :bob foaf:age "23"^^xsd:integer .
> >>
> >>
> >> Thus, it's the authoritative weight given to <>, by whoever, under whatever
> >> situation and circumstance, that leads to acceptance or rejection of the
> >> claims outlined e.g., those about the foaf:age of the entity identified
> >> by :bob .
> > 
> > I am not questioning that. Note, however, that your document is not
> > making a statement/claim about the claim regarding Bob's age (other than
> > asserting it, of course). The purpose of RDF*, and of RDF reification,
> > is to allow you to do so (within your document or within another of your
> > documents).
> > 
> > Best,
> > Olaf
> > 
> >>
> >> If we get the world we a modeling for clear, other bits of the problem
> >> will become clearer.
> >>
> >> Conclusion:
> >>
> >> In my opinion, we need a complete example that's relatable to the world
> >> that we are describing using RDF sentences :)
> >>
> > 
> > 
> 


Received on Monday, 12 August 2019 07:18:11 UTC

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