Re: Interpretation of RDF reification

In http://lists.w3.org/Archives/Public/www-rdf-comments/2004JanMar/0050.html
Pat Hayes also provides a good explanation of this point (that is, if 
Dan will forgive dragging Superman into the discussion again!  You also 
should substitute "Lois" for "Louis" in reading Pat's text.)  Pat also 
has some useful things to say about "alternative ways to encode de dicto 
assertions".

--Frank

Joshua Tauberer wrote:
> Dan Brickley wrote:
>> Let's ask it if the resource <registrar-1.rdf> is the dc:source of an
>> rdf:Statement
>> that has a predicate 'wife', subject
>> <tag:danbri.org:2006:people:charlie> and
>> object <tag:danbri.org:2006:people:alice>:
> 
> To recap, the moral of Dan's story is that RDF-reification doesn't track
> the actual URI someone used in a document, and this leads to
> non-intuitive semantics in this case:
> 
> _:s1 rdf:type rdf:Statement .
> _:s1 rdf:subject ex:bob .
> _:s1 dc:source <registrar-1.rdf> .
> 
> ex:bob owl:sameAs ex:charlie .
> 
> ASK: { ?s rdf:subject ex:charlie  .
>        ?s dc:source <registrar-1.rdf> . }
> --> YES
> 
> Two minor points to add to Dan.  First, as Dan points out,
> RDF-reification isn't appropriate for tracking the actual URIs people
> are using in documents.  The reason for this, though, is that in RDF,
> URIs aren't things we can refer *to*.  There's no way to assert
> something about a particular URI itself, i.e. that *that* URI was used
> in some document, unless you create a new vocabulary.  (That makes a lot
> of sense, really, because how would you ever know if a URI was there to
> mean the denoted entity, or the URI itself?)
> 
> The second point is that while the SPARQL query might be unintuitive, we
> actually have the same problem in English.  In semantics this is called
> the "de re"/"de dicto" distinction.  To roughly translate the SPARQL
> query into English we get:
> 
> Q:  "Does <registrar-1.rdf> refer to a man named Charlie?"
> 
> This question is ambiguous and would be true in both of these situations:
> 
> 1)  I know someone named Bob Smith.  I have a document <registrar-1.rdf>
> which mistakenly thinks Bob's name is Charlie.   About Bob
> <registrar-1.rdf> says "Charlie is nice." (de dicto)
> 
> 2)  I know someone named Charlie Smith.  About him, <registrar-1.rdf>
> says "Mr. Smith is nice." (de re)
> 
> In the first case, <registrar-1.rdf> refers to a man using the name
> Charlie even though that's not his real name.  (But the answer to the
> English question about could still be 'yes'.)  This is the 'desired' RDF
> interpretation in Dan's use case.
> 
> In the second case, <registrar-1.rdf> refers to a man, who is named
> Charlie, but without using that name.  (And you could still answer 'yes'
> to the English question.)  This is actually what RDF defines, and in
> this light a 'yes' answer to the SPARQL query also makes a lot of sense.
>  So while in English both the de dicto and de re readings are available,
> in RDF you only have de re interpretations of URIs.
>

Received on Thursday, 23 March 2006 23:03:49 UTC