- From: Michael Schneider <schneid@fzi.de>
- Date: Sun, 19 Dec 2010 14:15:57 +0100
- To: "Sampo Syreeni" <decoy@iki.fi>, "Melvin Carvalho" <melvincarvalho@gmail.com>
- Cc: "Semantic Web" <semantic-web@w3.org>
Hi Melvin and Sampo!
Sampo Syreeni wrote:
>On 2010-12-17, Melvin Carvalho wrote:
>
>> Since RDF is a set, the duplicate triple is disgarded. So Alice still
>> is described as owning one dog.
>
>Alice owns _1: which is a dog, alice owns _2: which is a dog, which are
>not necessarily the same unless by some other logic we can conflate
>them.
One has to distinguish between the syntactic and the semantic situation.
Syntactically, the graph
G1 := {
:alice :owns _:x1 . _:x1 rdf:type :Dog .
:alice :owns _:x2 . _:x2 rdf:type :Dog .
}
consists of four pair-wise different RDF triples, i.e. it is a set of size
4. On the other hand, the graph
G2 := {
:alice :owns _:x1 . _:x1 rdf:type :Dog .
}
is only a set of size 2, and therefore /syntactically/ different from G1 or,
more precisely, there is no RDF graph isomorphism modulo blank nodes between
G1 and G2.
Semantically, however, under all of the semantics of RDF(S), OWL 2 Full and
OWL 2 DL, G1 is equivalent to G2, i.e. the two graphs have exactly the same
/semantic/ meaning. The reason is that all of the mentioned semantics
interpret blank nodes (when used as anonymous individuals) as existential
variables.
Cheers,
Michael
--
Dipl.-Inform. Michael Schneider
Research Scientist, Information Process Engineering (IPE)
Tel : +49-721-9654-726
Fax : +49-721-9654-727
Email: michael.schneider@fzi.de
WWW : http://www.fzi.de/michael.schneider
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Received on Sunday, 19 December 2010 13:16:35 UTC