W3C home > Mailing lists > Public > semantic-web@w3.org > December 2006

Re: Can there be a URI for the concepts "I", "you", "this", "it", "here", "there", "now", etc.?

From: John Black <JohnBlack@kashori.com>
Date: Mon, 18 Dec 2006 18:13:43 -0500
Message-ID: <03e901c722fa$3b41b9c0$6601a8c0@kashori001>
To: "Joshua Tauberer" <jt@occams.info>
Cc: <semantic-web@w3.org>

> John Black wrote:
>> Are the following URI allowable according to web and semantic
>> web standards? Are they ambiguous? Are they useful? In each case,
>> the referent would depend on the context of the use[1] of the URI.
>> http://kashori.com/ontology/indexicals.owl#I
>> http://kashori.com/ontology/indexicals.owl#you
>> http://kashori.com/ontology/indexicals.owl#this
>> http://kashori.com/ontology/indexicals.owl#it
>> http://kashori.com/ontology/indexicals.owl#here
>> http://kashori.com/ontology/indexicals.owl#there
>> http://kashori.com/ontology/indexicals.owl#now
> I think one of the major benefits of RDF is that applications completely
> oblivious to any schemas can still at least make one conclusion about
> URIs, which is that if two documents use the same URI, they are
> referring to the same thing.  Context-dependent URIs break this.  It
> might be fine in some cases, but in general it would break the principle
> that <indexicals.owl#I> refers to the very same thing no matter where it
> appears.
>> Therefore they would only be of use if they could be embedded in a
>> structure that specified a context.
> That would be fine, except afaik the only way to publish a triple in an
> embedded context is with N3 formulas.  You can't, for instance, create
> an embedded context in RDF/XML.  (It wouldn't be sufficient to add a
> triple to an RDF/XML document to say "hey, this is one of those
> documents where you interpret <indexicals.owl#I> as ME" because it
> doesn't solve the problem that oblivious applications won't know to do
> that.)
> But, there is a way to get around these problems, which is to use some
> indirection.  Actually, that actually parallels the real-world side of
> things.  That is, we're not all named "I" (in the sense that a URI is a
> name for something).  "I" is really a function from a context to an
> individual.  The closest thing to a function in RDF is a predicate, so
> you could do this (in N3):
> <> indexicals:isBeingReadBy _:you .
> <> indexicals:isBeingReadAtLocation _:here .
> (then you go on to make assertions about _:you and _:here.)
> where <> is the URI for the document itself,

I think it is ironic that your example of how to avoid the need for
indexicals uses the one indexical URI that RDF can't seem to do without,
that is: <>. or rdf:about="".  Don't oblivious applications use this

It is also interesting that in spite of the obvious utility of it, this URI 
has no
formal semantics since the RDF Semantics standard says that it "...does not
provide any analysis of indexical uses of URI references, for example to
mean 'this document'." [1]

1. http://www.w3.org/TR/rdf-mt/

>  and _:you and _:here are
> bnodes.  Like this, an application isn't going to make the mistake that
> the same person is the "I" of every document.  Here it says "someone is
> reading the document", and just when the applications understands
> indexicals:isBeingReadBy it can say "Oh, and _:you is actually me!".
> (I'm not positive that that actually solves every problem, but it seems
> to be a step in the right direction.)
> -- 
> - Josh Tauberer
> http://razor.occams.info
> "Yields falsehood when preceded by its quotation!  Yields
> falsehood when preceded by its quotation!" Achilles to
> Tortoise (in "Gödel, Escher, Bach" by Douglas Hofstadter)
Received on Monday, 18 December 2006 23:16:04 UTC

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