Thanks Drummond.
Here are a few more thoughts:
1) I think that h:correlation (c. 2005) is the same as oguid:identical [1] (c. 2008) although I've not studied that too carefully. A quote from [1]:
The property oguid:identical indicates two resources
are co-referent.
In other words, they refer to the same real world thing.
Open GUID identity is defined pragmatically as referring to the
same concept beyond a reasonable doubt.
The major determinant is if the average human perceives the
resources as referring to the same thing.
The linking implication can be described as being between OWL sameAs
and RDFS seeAlso.
The sameAs property declares equivalence of semantic
representations; thus it should be used carefully to avoid confusing
logical reasoners.
The seeAlso property provides additional information;
nothing useful can be inferred from the link.
The identical property declares equivalence of
referents; thus it allows reasoners to use local representations while
still maintaining global context.
2) The concept of coreference [2] may also be helpful.
3) In Higgins the to co-referents must exist in different contexts.
With that as background, I'd like to say that it would be great if we could arrive at a precise semantic (irrespective of predicate name, $ word, etc.) that we could all use. If this TC comes up with a compatible but more precisely worded definition, I'd like nothing more than to copy/paste that definition into [3].
On Jun 25, 2010, at 1:03 AM, Drummond Reed wrote: > Paul wrote:
> Agreed (although I think you meant "symmetric" vs. transitive)
Paul, you're right, we did mean symmetric.
BTW, though we spent the last half of today's telecon discussing this issue, and agreed that the full $is semantics --- i.e. the semantics of a full identity relation -- is too strong for just "observed correlation", we didn't yet get into either:
1) What the precise definition would be for this weaker form of identity relation.
2) What the XDI $word for it would be.
I think the TC is open to suggestions for both. My suspicion is that the definition is probably along the lines of one of the four options discussed in http://www.w3.org/2009/12/rdf-ws/papers/ws21 (probably "4.1 Same Thing As But Referentially Opaque" or "4.2 Same Thing As But Different Context" or some combination of these two).
My only suggestion to a $word for this weaker form is $as. Example:
=drummond/$as/@golfclub+member!43
The semantics of $as would be "an identity relation between two XDI subjects in which there is not a requirement that all properties of one subject apply to the other and vice versa, nor a requirement that for XDI statement consistency across their respective XDI graphs."
That's just a strawman - hack away.
=Drummond
On Thu, Jun 24, 2010 at 2:10 PM, Paul Trevithick <ptrevithick@xxxxxxxxx> wrote:
Agreed (although I think you meant "symmetric" vs. transitive)
On Jun 24, 2010, at 3:22 PM, Barnhill, William [USA] wrote:
From my standpoint I've always thought of the XDI synonym
dollar word, which is now $is, as mapping to owl:sameAs. I briefly thought it
might be better to map to something a little weaker, skos:closeMatch, but came
back around to believing it should map to owl:sameAs. Another reason I think
h:correlation couldn't map to $is is that h:correlation is specifically not
a transitive property according to the Higgins XDI Harmonization wiki,
whereas $is must be.
Bill
From: Paul Trevithick
[mailto:ptrevithick@xxxxxxxxx]
Sent: Thursday, June 24, 2010 2:15
PM
To: Giovanni Bartolomeo
Cc: OASIS - XDI
TC
Subject: Re: [xdi] reactions on paper "When owl:sameAs isn?t the
Same..."
Giovanni,
Last week it was proposed that h:correlation is the same as $is, but on
further reflection I don't think that's right. I think $is is
equivalent in semantics to owl:sameAs. Joseph and I discussed this a bit today
on the XDI harmonization portion of the weekly Higgins call. In Higgins
h:correlation means: representing the same thing in different contexts. The
following para is copied from [1] (BTW, we use the term entity instead of
resource):
h:correlation is subtly different from owl:sameAs. It is statement made by a human observer that the
source and target of this link are believed to be alternative representations
of the same real world person or object. A single, natural person would thus
be represented by different entities in different contexts. This linkage does
not presume that the entire set of attributes across these entities, if they
were brought together and combined, is necessarily logically consistent. The
ontologies in the two contexts may be such that each of the two
representations cannot be merged and remain logically consistent. For this
reason Higgins does not use owl:sameAs which does imply this ability to directly merge
representations. h:correlation is stronger than rdfs:seeAlso but weaker than owl:sameAs.
On Jun 24, 2010, at 1:40 PM, Giovanni Bartolomeo wrote:
Hello,
having had time this week to look at
these Drummond suggested readings:
?When owl:sameAs isn?t the Same: An
Analysis of Identity Links on the
Semantic Web?, by Harry Halpin,
Ivan Herman, and Patrick J. Hayes
?RDF and XML: Towards a Unified Query
Layer?, by Nuno Lopes, Stefan
Bischof, Orri Erling, Axel Polleres,
Alexandre Passant, Diego
Berrueta, Antonio Campos, Jé?rôme Euzenat,
Kingsley Idehen, Stefan
Decker, Sté?phane Corlosquet, Jacek Kopecky
?, Janne Saarela, Thomas
Krennwallner, Davide Palmisano, and Michal
Zaremba
(both will be presented at nextcoming W3C RDF workshop,
http://www.w3.org/2009/12/rdf-ws/)
I would like to share with you some
thoughts on how I believe XDI
and XRI non-opaque identifiers could
nicely address some issues
presented there - especially in the first
article.
Could you
insert this topic into today's or next week's phc agenda?
Thank you
very much,
Giovanni
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