Re: Managing Co-reference (Was: A Semantic Elephant?)

On 15 May 2008, at 21:30, Aldo Gangemi wrote:
> Issue 1: managing to suggest the rationale of owl:sameAs  
> appropriately, i.e. in a harmless way for future usages (Aldo,  
> Michael)
> Issue 2: distinguishing "data provision" vs. "representational"  
> usages of owl:sameAs (Yves)
> Issue 3: need for another operator, e.g. representing equality under  
> a closed set of properties (Geoff, Harry), or some relaxed  
> rdfs:sameAs (Jim)
>  Issue 3a: using another existing relation, such as skos:related or  
> rdfs:seeAlso, but these are either too weak (rdfs:seeAlso), or  
> constrained (skos:related)
> Issue 4: need for a semiotic grasp over co-reference, maybe outside  
> formal semantics (Bernard, Peter)

I think you missed Jeremy Caroll's suggestion that at times you need  
to decide what owl:sameAs you trust and apply different one's under  
different circumstances. So if you know someone is publishing data,  
and they can't conceptually distinguish between spain the geopolitical  
region and spain the political entity then you can apply certain  
relations. In fact sometimes you may even have to decide that some  
people confuse two relations and decide to apply some rule to their  
utterances.

CONSTRUCT { ?a rdfs:seeAlso ?b }
WHERE {
    GRAPH ?g { ?a owl:sameAs ?b . }
    ?g said:by :george .
}

It is I think inescapable that we will need such rules. But of course  
we should try as much as possible to develop logics that avoid the  
need for them.

It would be good to have a few clear examples. I like the Berlin one.  
How should one relate the following things

<http://sws.geonames.org/2950159/>
<http://sws.geonames.org/2950157/>
<http://dbpedia.org/resource/Berlin>

Are rules the only way to go about it?

The criticism of dbpedia is I think wrong at two points:
   - they don't confuse documents and resources
   - if they make mistakes linking resources from different vocabs  
that is something that can be corrected. (It would help if dbpedia  
were editable like wikipedia)

Finally on the topic of owl:sameAs slowing things down, I was  
wondering how rdf databases can be built to do efficient reasoning  
over these things? Should they have special rules for owl:sameAs by  
for example deciding for every owl:sameAs group a canonnical  
identifier that collects all the merged relationships?

"http://www.w3.org/People/Berners-Lee/card#i" is canonicalURI of
                    <http://www.w3.org/People/Berners-Lee/card#i>,
                    <http://www4.wiwiss.fu-berlin.de/bookmashup/persons/Tim+Berners-Lee 
 >,
                    <http://www4.wiwiss.fu-berlin.de/dblp/resource/person/100007 
 > .

So that the DB just puts all the relations on <http://www.w3.org/People/Berners-Lee/card#i 
 > .

Should that be built right into triple or quad stores? (Does it work  
with quad stores?)
Is it more efficient?

Henry