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Re: log:forSome/#rdfms-identity-anon-resources

From: Frank Manola <fmanola@mitre.org>
Date: Thu, 28 Jun 2001 17:00:46 -0400
Message-ID: <3B3B9AFE.376DDDA0@mitre.org>
To: Dan Connolly <connolly@w3.org>
CC: pat hayes <phayes@ai.uwf.edu>, w3c-rdfcore-wg@w3.org
Dan Connolly wrote:
> 
snip
> A prolog query
>         author(X, "b"), title(X, "f e")
> is a request to prove the theorem
> 
>         (exists (?x) (author ?x "b") (title ?x "f e))
> right? and the query results are proofs; i.e. substitutions
> of the variables that show that it's satisfyable.
> 
> That's how queries work, right? They're existential formulas,
> and the job of a query engine is to give proofs, by
> example, of the theorem. This is completely traditional, no?
> 
> [[[
> Free variables in a query
> are assumed to be existentially quantified.
> ]]]
> 
> --        Knowledge Interchange Format
> http://logic.stanford.edu/kif/dpans.html
> Thu, 25 Jun 1998 22:31:37 GMT

Sorry if this appears to be barging in out of the blue, but the KIF spec
you cited says:

* Note that the significance of free variables in quantifier-free
sentences depends on context. 
* Free variables in an assertion are assumed to be universally
quantified. Free variables in a 
* query are assumed to be existentially quantified. In other words, the
meaning of free variables 
* is determined by the way in which KIF is used. It cannot be
unambiguously defined within KIF itself. 
* To be certain of the usage in all contexts, use explicit quantifiers

Based on this, it seems to me that we'd need to say more than that we're
interpreting anonymous resources as free variables.  We'd also need to
say whether we're expressing an assertion or a query.  So far, I thought
we'd been assuming that RDF was making assertions.  On the other hand,
it might be that RDF is in the same position as KIF is here, and we'd
need to take context into consideration.   

--Frank

-- 
Frank Manola                   The MITRE Corporation
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Received on Thursday, 28 June 2001 17:01:18 EDT

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