W3C home > Mailing lists > Public > www-rdf-interest@w3.org > April 2002

RE: Explicit Disambiguation Via RDF bNodes, more Process

From: Joshua Allen <joshuaa@microsoft.com>
Date: Sun, 28 Apr 2002 19:09:42 -0700
Message-ID: <4F4182C71C1FDD4BA0937A7EB7B8B4C104F05F05@red-msg-08.redmond.corp.microsoft.com>
To: "Murray Spork" <m.spork@qut.edu.au>, <www-rdf-interest@w3.org>
Is it fair to say that your proposal is:

1) Assume that a URI identifies a unique thing (and an http: URI identifies a "web page")
2) Assume that it is OK to merge assertions that use the same URI
3) Acknowledge that sometimes you might get metadata where a single URI is used inconsistently.
4) Metadata with inconsistencies may or may not be able to be merged, depending on information available and techniques used to merge it.  It may be possible to merge it, or it may simply be necessary to ignore it.

If so, then I completely agree with you.  The only part I am adding is:

5) People SHOULD NOT use http: URIs to refer to things like cars
6) If they do, there is no guarantee that their metadata will be able to participate in the semantic web.

Joshua Allen
Microsoft WebData XML

> -----Original Message-----
> From: Murray Spork [mailto:m.spork@qut.edu.au]
> Sent: Sunday, April 28, 2002 6:00 PM
> To: www-rdf-interest@w3.org
> Hi all - hope you don't mind me jumping in here.
> Bill de hÓra wrote:
> [...]
>  > Speaking for myself, I'm not trying to be gratuitous. You're
>  > arguing from an extreme point ("rare cases where a word will be
>  > used with [a] connotation that is opposite its normal
>  > connotation"), but really we're on a sliding scale. Away from the
>  > extremes, people get their meanings mixed every day (i.e., "violent
>  > agreement"). I don't see how we expect things to be different on a
>  > web sprinkled with RDF.
>  >
>  > But I simply can not take RDF assertions off the web and merge them
>  > with my local data unless I have some confidence that the each URI,
>  > http or otherwise is referring to only one thing. But in an open
>  > system I can never be certain. We need to get over this.
> I agree. Joshua's phrase "gratuitous ambiguity" indicates that he
> thinks there is an attempt to "build in" ambiguity into the model.
> I'd rather think of it as just an acceptance that representation of
> identity is in reality ambiguous - attempting to abstract away that
> ambiguity is not likely to succeed IMO.
>  > What I can do is calculate a probability that a URI seen in two
>  > different data sets refers to the same thing (that's my instinctive
>  > reaction to this problem). Or I can possibly determine sameness by
>  > comparing the properties hanging off the URIs, or doing some type
>  > inference, which is what I understand Danny's suggesting.
> Again I agree - is this really a problem that needs solving in RDF? - or
> is it (as I suspect) a problem to be solved with appropriate tools?
> If doing some sort of probabilistic plausibility analysis to resolve
> ambiguous identifiers is considered "vodoo" - then the idea of a model
> where no possibility for ambiguous identifiers exists is (IMO) so much
> more far-fetched.  If we can't write the tools to substantially solve
> this problem then IMO the SW is a non-starter and no attempt to engineer
> out ambiguity can save it.
> My suggestion would be that in the absence of conflicts
> (inconsistencies) we assume URIs identify an unambiguous thing.
> But if in merging rdf graphs conflicts arise (for example where 2
> objects are ostensibly the same object (they have the same URI) but are
> used in statements that imply incompatible typing)- then we resolve the
> inconsistencies at that point - using the appropriate tools and
> techniques (such as that "qua" technique suggested by Danny Ayers).
> This seems to me to be a practical and workable solution that hits the
> appropriate 80/20 point.
> Cheers,
> --
> Murray Spork
> School of Information Systems, Faculty of Information Technology
> The Redcone Project
> http://redcone.gbst.com/
> Queensland University of Technology, Brisbane, Australia
> Phone: +61-7-3864-4246
> Email: m.spork@qut.edu.au
Received on Sunday, 28 April 2002 22:10:19 UTC

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