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

From: Sandro Hawke <sandro@w3.org>
Date: Mon, 21 May 2001 14:53:49 -0400
Message-Id: <200105211853.OAA14691@hawke.org>
cc: pat hayes <phayes@ai.uwf.edu>, www-rdf-logic@w3.org

(replying to myself; pointing out my error)

> 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.
> 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.

Dan Connolly pointed me to 
which shows that KIF (and thus presumably FOL) does not have the unique
names assumption -- it's inference systems that typically have it. 

So now I'm looking at
and thinking RDF layer 1 is equivalent to KIF restricted (by removing
grammar productions) to this:

<objconst> ::= a word denoting an object 
<relconst> ::= a word denoting a relation 
<term> ::= <objconst> | <relconst>
<sentence> ::= <relsent> | <logsent>
<relsent> ::= (<relconst> <term> <term>)
<logsent> ::= (and <sentence> <sentence> <sentence>*)

I bet this is a lot smaller than the core you have in mind for
IEEE-KIF.   :-)

     -- sandro
Received on Monday, 21 May 2001 14:53:53 UTC

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