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Re: RDF dataset semantics again

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Tue, 21 Aug 2012 22:21:55 +0200
Message-ID: <5033EDE3.1000403@emse.fr>
To: Pat Hayes <phayes@ihmc.us>
CC: Ivan Herman <ivan@w3.org>, RDF WG <public-rdf-wg@w3.org>
Le 21/08/2012 21:48, Pat Hayes a écrit :
>> Antoine, I have the impression that we are actually in agreement.
>> The document we have put forward has two essential points:
>> - we would have a default semantics in the form of the quoting
>> semantics
> Whoa. I do not know what y'all mean by a "default semantics". Is this
> a default that can be overridden? If so, I know of NO semantic theory
> anywhere in logic or linguistics that can provide this. If y'all want
> this, you are on your own.
> If not, what exactly is it supposed to mean?
> Pat


When I say default, I just mean that in absence of indication that you 
can do additional deduction, you have to rely on minimal constraints. 
For instance, if I have the triples:

  :me  rdf:type  foaf:Person .
  foaf:Agent  rdf:type  rdfs:Class .

then, by default (i.e., in absence of further knowledge), I cannot conclude:

  :me  rdf:type  foaf:Agent .

but if I ever happen to know about the FOAF Ontology and I agree it is 
true, I can make this conclusion. Now, for datasets, it would mean that 
in absence of further knowledge (and "further knowledge" could take a 
special form not yet known) then from the dataset:

  <g> { :me  rdf:type  foaf:Person . foaf:Person  rdfs:subClassOf 
foaf:Agent }

I cannot conclude something like:

  <g> { :me  rdf:type  foaf:Agent }

However, if I do know, with additional stuff in the dataset, that the 
semantics is "semantics (c)" as describe in my previous email, then I 
can make that inference. It's not breaking a century of theory in 
logics, don't worry.

In summary, it just amount to saying that additional knowledge brings 
more deductions, which is in line with everything done historically in 
circles of logicians.

The "only" thing missing is how we are going to tell the world that 
there is this extra knowledge, and how this can be formalised precisely.

Nonetheless, I have a draft of an email that discuss this topic and I'm 
still not sure what the "default" semantics should be...

Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
Tél:+33(0)4 77 42 83 36
Fax:+33(0)4 77 42 66 66
Received on Tuesday, 21 August 2012 20:22:36 UTC

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