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Re: Semantics document, new rule 'gl'

From: Graham Klyne <gk@ninebynine.org>
Date: Wed, 17 Dec 2003 12:13:47 +0000
Message-Id: <>
To: pat hayes <phayes@ihmc.us>
Cc: w3c-rdfcore-wg@w3.org

At 06:48 16/12/03 -0800, pat hayes wrote:
>>Rule: lg1
>>If E contains: uuu aaa lll .
>>Then:          uuu aaa _:nnn.  _:nnn foo:sameAs lll .
>>(where _:nnn is allocated as described for rule 'lg'.)
>>Rule: gl1
>>If E contains: uuu bbb _:nnn .  _:nnn foo:sameAs lll .
>>Then:          uuu bbb lll .
>>(The 'foo:sameAs' property is intended to appeal to the owl:sameAs 
>>property, without getting entangled with the owl semantic conditions on 
>>I.e., a foo:sameAs b does not necessarily mean that I(a) == (b), just that
>>    a p c . <=> b p c .
>>    d q a . <=> d q b .
>>for all syntactically allowable c, d, p, q.)
>Right, exactly. That is what is needed in an implementation: to treat the 
>literal and its allocated bnode *in exactly the same way* wherever 
>syntactically possible.  In fact, the best way to handle this would be to 
>actually use the literal in subject position when applying the rules, if 
>your implementation can handle that, and just ignore rules lg and gl.  Or, 
>maybe, apply rule lg to everything, *including the proposed conclusion* 
>which would be closest to standard computational-logic practice and would 
>obviously avoid the need for that silly rule gl; in effect it would just 
>eliminate literals altogether in favor of blank nodes.


I could use the literal-as-subject approach, but I wanted (for no 
particular reason other than a sense of tidiness) to be able to check 
proofs that were based as closely as I could manage on the RDF formal spec.


Graham Klyne
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Received on Wednesday, 17 December 2003 07:19:35 UTC

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