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Re: regrets & skolem predicates

From: William Waites <ww@styx.org>
Date: Thu, 21 Apr 2011 13:41:30 +0200
To: Pat Hayes <phayes@ihmc.us>
Cc: RDF-WG <public-rdf-wg@w3.org>
Message-ID: <20110421114130.GL9393@styx.org>
* [2011-04-20 16:10:23 -0500] Pat Hayes <phayes@ihmc.us> écrit:

] On Apr 20, 2011, at 9:20 AM, William Waites wrote:
] > Unfortunately I won't be able to make the call today due to a
] > conflicting commitment.
] > 
] > However, a thought just occurred to me - what happens when someone
] > uses a skolem constant - now a URI - as a predicate?
] Nothing happens. What did you think might happen?

Oh well, the world might end?

There is nothing really new here, people have always been free to mint
predicates as they like. But so far I think we have seen a fair amount
of conservatism here. A special URI space for skolem constants might
encourage people to make many ad-hoc predicates - there are some
problems for which this may make sense (some kinds of treatments of
similarity and relevance for example, teasing apart "incorrect" uses
of owl:sameAs come to mind).

This doesn't pose a theoretical problem but may pose a practical one
since at least some stores make an assumption that the number of
distinct predicates will be relatively small as an optimisation.

That, and the implications of a store trying to turn these skolems
back into bnodes - if :s _:b1234 :o is illegal but :s <blank:b1234> :o
is not, what does that do to equisatisfiability?

William Waites                <mailto:ww@styx.org>
http://river.styx.org/ww/        <sip:ww@styx.org>
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Received on Thursday, 21 April 2011 11:41:55 UTC

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