Re: RDF* and grouping relation properties

First, owl:sameAs is not part of RDF, nor RDFS.  So as far as RDF and RDFS are
concerned owl:sameAs has no special semantics.

But I expect you are asking why aren't statements with different properties
supposed to be mapped to different elements of the domain by IS.  (See
https://www.w3.org/TR/rdf11-mt/#simple-interpretations.)  There is no reason
for this in RDF or RDFS.  

If different properties meant that two nodes had to be mapped onto different
domain elements then a lot of RDF would change.  For example,

ex:BO1 ex:name "Barack Obama", ex:spouse ex:MO.

and

ex:BO2 ex:name "Barack Obama", ex:spouse ex:MO, ex:child ex:SO.

would have to represent different domain elements, i.e., different individuals
in the world.

But then what happens if

ex:BO1 ex:child ex:SO .

is added to the graph?

All of a sudden these two nodes *could* represent the same person?


peter


PS: Yes, the shading from complete formality to relative informality is intended.


On 6/22/20 7:39 AM, Andy Seaborne wrote:
>
> On 21/06/2020 22:01, Patrick J Hayes wrote:
>>
>>
>>> On Jun 21, 2020, at 5:14 AM, thomas lörtsch <tl@rat.io <mailto:tl@rat.io>>
>>> wrote:
>>>
>>>
>>>
>>>> On 18. Jun 2020, at 17:44, Tim Finin <finin@umbc.edu
>>>> <mailto:finin@umbc.edu>> wrote:
>>>>
>>>> While experimenting with RDF* I realized one issue: for some relations,
>>>> we may have several properties that should be treated as a group.  For
>>>> example, the provenance of a relation extracted from the text of a web
>>>> page might include a link to the page and the date retrieved.
>>>>
>>>> Using the following two RDF* expressions merges the four properties so
>>>> that we can no longer determine which :source and :retrieved values go
>>>> together.
>>>>
>>>> << :man :hasSpouse :woman >>
>>>>    :source <http://foo.com/>;
>>>>    :retrieved "2020-06-17"^^xsd:date .
>>>> << :man :hasSpouse :woman >>
>>>>    :source <http://bar.com/>;
>>>>    :retrieved "2020-01-01"^^xsd:date .
>>>>
>>>> Using a traditional RDF reification approach maintains the pairing.
>>>>
>>>> :man2 :hasSpouse :woman2 .
>>>> [ ]  a rdf:Statement ;
>>>>     rdf:subject :man2 ;
>>>>     rdf:predicate :hasSpouse ;
>>>>     rdf:object :woman2 ;
>>>>    :source <http://foo.com/> ;
>>>>    :retrieved "2020-06-17"^^xsd:date .
>>>> [ ] a rdf:Statement ;
>>>>    rdf:subject :man2 ;
>>>>    rdf:predicate :hasSpouse ;
>>>>    rdf:object :woman2 ;
>>>>   :source <http://bar.com/>;
>>>>   :retrieved "2020-01-01"^^xsd:date .
>>>
>>> In my understanding of the RDF Standard Reification semantics your two
>>> blank nodes are owl:sameAs as the reification quad refers to the abstract
>>> triple type, not any concrete token.
>>
>> Correct. But bear in mind that none of the semantic guidance in the RDF
>> specs for reification is normative. RDF reification has /no/ normative
>> semantics.
>
> I'm confused.
>
> Why don't the additional :source, :retrieve triples differentiate the blank
> nodes making them not owl:sameAs?
>
>
>
>

Received on Monday, 22 June 2020 12:19:58 UTC