RE: Proposed issue: What does using an URI require of me and my software?

> From: pat hayes, Sent: Friday, September 26, 2003 10:01 PM
> > From: > From: Tim Berners-Lee, Sent: Friday, September 26, 2003 10:42 AM
> >
> >In-Reply-to Bijan's original
> ><http://lists.w3.org/Archives/Public/public-sw-meaning/2003Se
> p/0054.html> 
> >, clarifications.
> 
> <big snip, mostly cuz I agree with it all>
> 
> >7 Naive protocols and safe operating procedures
> >
> >Actually, the whole question of damage raises another distinction.
> >Most of the "intuition pump" example is about things going wrong.
> >
> >I think we may have to consciously distinguish in the design
> >of the semantic web in general between the normal expected ways
> >of going about things, which we can show will wok, and the
> >operating procedures which will allow one to operate safely in
> >a potentially hostile environment.
> 
> Agreed, important point.
> 
> >Example: a purchase choice system choses the cheapest product
> >which is offered as being compatible with an hp:p314159.
> >The naive protocol is for the seller to offer the 
> compatibility and price
> >system in the catalogue which you get by dereferencing the
> >part URI, and the buyer loading the catalogs into its kb.
> >A more secure system filters the catalogs for lies about
> >which product is best.  You can define conformance with some
> >market protocol in that the catalog only has data of a given form,
> >but you still want to be careful about things which break it.
> >
> >Focussing, then, back on what an RDF document means, which
> >was the original narrower scope than all of this, I would say we have
> >to first define the naive protocol,
> >
> >- Use of an HTTP URI as a symbol in an RDF statement
> >  refers to one thing which the URI owner intended.
> 
> Why? Why do we need to say that it refers to ONE thing? Even as a 
> normal assumption. Surely, all we need here is the following:
> 
> >
> >- The URI owner puts true, consistent, hum &/or machine
> >readable information in the
> >   document that you get should you chose to dereference the URI.
> 
> Right. Now, lets suppose that as well as there being a document that 
> you get, that the document says that it refers to something.  (Eg the 
> document at http://www.w3.org/2001/XMLSchema says "This document 
> describes the XML schema namespace.") Under those conditions, then, 
> accepting the truth of the document amounts to accepting that it 
> refers to some unique thing. It might say that more formally in some 
> way, or it might not say it at all.  But it seems to me that all we 
> need to stipulate is that if it says something, then there is a 
> ceterus paribus, normal, all things considered, good practice 
> assumption being made by everyone involved that whatever it says, is 
> being considered to be true. That seems the least we can reasonably 
> say about this, and I think it is all we need to say about it; and it 
> has the great merit of being susceptible to precise semantic 
> description which applies both to SW stuff and NL stuff that you 
> might find there, and it treats the URI according to existing Web 
> architectural principles (you ping it, you get a representation, you 
> assume its true) and it seems to conform with existing practice, 
> insofar as there is one, and it cuts through useless debates. What 
> exactly does http://www.w3.org/2001/XMLSchema denote? Well, use the 
> Web, take a look, and see what it says.  If that doesn't tell you, 
> nothing will.

I agree with this.  But why not go on and say that it should be 
formal?  If you want to define a URI for use in RDF then you must 
embed an <> rdf:type ontology:ClassOfThisURI in the document at 
that URI.  The architecture should then specify that any URI 
that does not have such a tag defaults, for the purpose of 
meaning in RDF to <> rdf:type rdf:Thing.  So now all such 
undefined URIs can be converted into logical statements that 
assert the existence of Thing(URI).  An owner of a URI thus 
defines its meaning by embedding such a tag.  Operationally, 
any use of this URI should be checked for conformity with 
this assertion.  That is, if you use that URI in RDF, then 
you must do so in a way that conforms to the assertion 
that it designates an individual of ontology:ClassOfThisUri.  
Then, logically, the entire web becomes a federated binary relation 
of dyadic tuples (uri,type) that can be used to test all uses of 
a URI.

Any use of a URI that defaults to type Thing will 
always conform.  Furthermore, if URI is of type 
ontology:ClassOfThisUri then any use of that URI as 
a ontology:SuperClassOfThisUri will also conform since any 
URI that conforms to a onto:Class will also conform to all its 
onto:SuperClasses. 

> We don't need to make this semantically dubious claim 
> that URIs denote uniquely. There isn't even any way to make sense of 
> that claim in many cases, and communication doesn't depend on it.
> 
> Pat
> 
> 
> >
> >- Nobody hijacks the domain name system, the LAN or the server,
> >  or an intervening proxy, or the user's computer, etc
> >
> >
> >If we could get that nailed down first, then afterwards we 
> could launch into
> >the questions of what happens when people lie, make mistakes,
> >fix mistakes, the net goes down, and so on, as to whether we should
> >make the best of it, model everything in an extra level of detail,
> >take someone to court or call the to discuss it over lunch, 
> et cetera.
> >
> >We can also define useful rules of friendly behavior which a 
> community
> >could adopt to make a working system within that community.
> >
> >Tim
> 
> 
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Received on Sunday, 28 September 2003 17:49:14 UTC