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

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Fri, 16 May 2008 01:11:14 +0100
Message-ID: <482CD122.2000601@ibiblio.org>
To: Peter Ansell <ansell.peter@gmail.com>
Cc: Jim Hendler <hendler@cs.rpi.edu>, Semantic Web Interest Group <semantic-web@w3.org>

Peter Ansell wrote:
> 2008/5/16 Jim Hendler <hendler@cs.rpi.edu>:
> Fwiw, seems to me what we need is rdfs:sameas - with owl: sameas being a
> special, more restricted, case - like rdf vs owl class defs
>   
>
> I agree. There is a big difference between being able to merge RDF
> graphs and merge OWL "Things".

There's a pretty convincing argument that it is likely impossible to get 
to manage co-reference completely down to the level of what Bernard 
calls the "signified" or most people think of "a thing in the real 
world." For those that missed the IRW2006 workshop, called "In Defense 
of Ambiguity" and its finally written down [1],  I'd recommend reading 
it for those interested in the argument that a URI can never really 
identify one thing, even with inverse functional properties :)

The best we can hope for is descriptions of these things and sharing 
those. This just doesn't apply to informal semantics of "things in the 
real world" but also to the formal semantics of any SemWeb language,  as 
any model-theoretic interpretation has lots of interpretations in a 
domain which will satisfy it, so that the "referent" is never pinned 
down exactly.
> I use owl:sameAs to do the former when
> the properties are all going to be relevant to both, but the two URI's
> still don't necessarily match a given whole-world OWL structure.
>   
Trying to get to the practical ramifications of the argument, so feel 
free to help me here if I've misinterpreted thigns. I think the real 
issue here is one again, not of resolving co-reference on some sort of 
"deep" level, but that of when to import descriptions, which on the 
Semantic Web are triples. In essence owl:sameAs is rather strong since 
for URI_1 owl:sameAs URI_2, every triple that  applies to URI_1 must 
also apply to URI_2 and vice versa. So, in essence, all these triples 
must be imported, no?
> rdfs:seeAlso has never been a big attraction to me due to its lack of
> actually saying anything about what you are going to get, possibly due
> to its colloquial use with FOAF and sending you off to a random foaf
> file for more information about an, as yet unnamed, entity.
>   
While rdfs:seeAlso does not have this constraint, i.e. it is just 
another predicate, so it doesn't really state anything. Should it 
followed? Should all triples in seeAlso be added to the graph of an 
agent encountering rdfs:seeAlso? Who knows? It seems "no."

What we seem to want is something like rdfs:seeAlso that forces one to 
import some statements, but not necessarily everything (ala 
owl:sameAs).  Perhaps the real issue is that people want some sort of 
"partial" importing of triples, i.e. a semantics for owl:imports (or 
something similar,). That one can say for URI_1 owl:kindaSameAs URI_2, 
where that means concretely some finite triples that apply to URI_1 also 
apply to URI_2, but not necessarily all . That's usually how humans 
communicate, by sharing "just enough descriptions" to get the job done, 
not necessarily buying everything.  But what would that mean 
implementation-wise? How can one avoid just having to "list" these 
triples and put them in via an owl:imports, but maybe bundle them up in 
some nicer manner?

Peter Patel-Schneider and Bijan Parsia had a nice paper on owl:imports 
this at IRW2006[2].

Anyways, if any of you are going to be at ESWC2008, remember we'll be 
debating these issues in depth at the IRSW2008 workshop:[3].

                -harry

[1]http://www.ibiblio.org/hhalpin/homepage/publications/indefenseofambiguity.html
(pre-print of article in IJSWIS 4(2) 2008 this year)
[2]http://www.ibiblio.org/hhalpin/irw2006/bparsia.pdf
[3]http://www.okkam.org/IRSW2008/
> Given that you are never sure how someone is going to utilise your OWL
> structures in future you cannot be held accountable for every
> statement you make retrospectively, particularly if the dependent
> vocabularies (or the assumptions of the person utilising the
> vocabulary) are the cause of the breakage.
>
>   
>> Sent from my iPhone
>>     
>
> (Cool!)
>
> Peter
>
>   
Received on Friday, 16 May 2008 00:11:57 GMT

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