W3C home > Mailing lists > Public > www-rdf-logic@w3.org > May 2001

Re: The Unique Names Assumption + RDF Layer 1 as Restricted FOL

From: pat hayes <phayes@ai.uwf.edu>
Date: Thu, 24 May 2001 14:34:54 -0500
Message-Id: <v0421010bb733104d4c39@[205.160.76.208]>
To: Sandro Hawke <sandro@w3.org>
Cc: www-rdf-logic@w3.org
>Back in February, you pointed out that my terminology when I talked
>about "generating unique names" (which I now call something like
>otherwise-unused names)

> was confusing, giving the existing terminology
>of the "unique names" assumption (the idea that distinct names denote
>distinct objects).
>
>I think we agree that it's impractical to have this assumption among
>names in a global (widely distributed) namespace, so if RDF documents
>are to all share one denotation map, then they must work without the
>unique names assumption.

Yes. There is no way to stop some other guy using names in a 
non-unique way. (However, what we could do is to allow people to 
assert that some namespace was unique-named, ie have 'limited-scope' 
unique naming. This would probably give enough functionality to the 
folk who want to use unique naming within some  database. But this is 
an aside.)

>I'm thinking that means RDF is not exactly ground atomic binary
>relationships.

I dont follow thatt. Ground atoms don't of themselves incorporate the 
unique names assumption.  They are kind of uniqueness-agnostic.

>I was trying to think of the RDF layer 1 language as FOL with a
>restricted syntax: only one predicate (of arity 3, call it "RDF"
>perhaps), no functions, conjunction as the only connective, no
>equality, no negation, ....  Anyway, it seems to me that the terms,
>rather than being constants, should all be existentially quantified
>variables: that makes them match our not having the unique names
>assumption.
>
>Does that seem right to you?

That makes sense, I guess, though I tend to think of logical  names 
as being  basically the same as existentially quantified variables, 
so I may not be following the contrast you are making here.

>(I'm not trying to open the floor for what a layer 1 language should
>be yet, just trying to characterize what I think it might be, which
>may help us when/if we do open the floor.)

Indeed.

Pat

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Received on Thursday, 24 May 2001 15:35:11 UTC

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