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RE: We don't need no stinkin' identity

From: pat hayes <phayes@ai.uwf.edu>
Date: Sat, 26 Apr 2003 18:25:59 -0500
Message-Id: <p05210614bad0c26cc24f@[10.0.100.12]>
To: "Larry Masinter" <LMM@acm.org>
Cc: uri@w3c.org

>Personally, I think the problem of grounding
>assertions in the real world is a Hard Problem,

Seems we agree on that.

>and that those who've been working on RDF or
>Semantic Web have tried to avoid this problem
>by wishful thinking that the "URI" could somehow
>be used as a universal semantic concept
>designator and that it would do the heavy lifting
>all by itself.

You have it backwards: RDF and the SW *don't* need to make this 
assumption, which is being imposed from elsewhere.  You won't find 
anything about grounding or designation in any of the RDF/S or OWL 
documents, and we are purging the fluff about "social meaning". In 
fact, the reason Im howling so loud about this issue is that this 
assumption (that URIrefs *must* by some magical process always be 
uniquely grounded) is FATAL to SW semantic theories. That's why I 
don't want RFC 2396 to say anything that can be interpreted this way.

>I just don't think it works, and no amount
>of wordsmithing in RFC 2396bis will actually
>help much.
>
>I'm all for the URI specification explicitly
>disclaiming this responsibility. For a proposed
>specific wording:
>
>>  What is a Resource? Can a URI be used to identify a Concept?
>
>>  This specification does not define the word 'resource' carefully,
>>  nor does it define how a URI can be used to 'Identify' a
>>  'Resource' with enough precision to allow URIs to be used
>>  as grounded terms in any kind of logic language.

Don't give the impression that logic requires grounding. It doesn't.

>First,
>>  note that the _semantics_ of a URI are not defined in
>>  this specification. Each URI scheme itself defines the
>>  relationship between URIs of that scheme and the resources
>>  they identify. In all known cases, that definition isn't
>>  enough to allow the URIs of that scheme to be used, by
>>  themselves, as unambiguous identifiers when trying to
>  > make logical assertions.

Again, the problem is not that the logic requires unambiguity; quite 
the reverse, in fact: it is that imposing unambiguity as a defining 
characteristic of URIs is logically incoherent.

Suggested modification, without the logic-bashing:

>  What is a Resource? Can a URI be used to identify a Concept?

>  This specification does not define the word 'resource' carefully,
>  nor does it define how a URI can be used to 'Identify' a
>  'Resource'. The _semantics_ of a URI are not defined in
>  this specification.  Each URI scheme itself defines the
>  relationship between URIs of that scheme and the resources
>  they identify or refer to.

The reason for the last three words is that it doesn't make sense to 
say that a URI identifies a *single* thing, in almost any logical 
language. (In fact, it doesn't make much sense in any language, IMO, 
but leave that aside for now.)

Pat Hayes

PS. That could also end, "...they are used to identify or refer to." 
if that reads better.



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Received on Saturday, 26 April 2003 19:26:01 GMT

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