Re: [RDF-CONCEPTS] Skolemization from David Booth on 2013-06-12 (public-rdf-comments@w3.org from June 2013)

From: David Booth <david@dbooth.org>
Date: Wed, 12 Jun 2013 15:17:03 -0400
To: "Sven R.Kunze" <sven.kunze@informatik.tu-chemnitz.de>
CC: Pat Hayes <phayes@ihmc.us>, Ivan Herman <ivan@w3.org>, public-rdf-comments <public-rdf-comments@w3.org>
Message-ID: <51B8C92F.3030802@dbooth.org>

On 06/12/2013 02:24 PM, Sven R.Kunze wrote:
>  >You are really going to confuse people if you say things like that.
>  >Skolemizing
>  >
>  >   _:b :foo :bar .
>  >
>  > into
>  >
>  >    skolem:b :foo :bar .
>  >
>  > (where skolem:b is a skolem URI) is *completely* different from changing
>  > it into
>  >
>  >    :bar :foo :bar .
>  >
>  > The former "does not effectively alter what can be validly derived from
>  > the graph", whereas the latter obviously does.
>
> I don’t see it. Why does the latter obviously affectively alter entailment?

Because :bar already appeared in the graph: it was not a new URI.

   skolem:b :foo :bar .

is not isomorphic to

   :bar :foo :bar .

David

Received on Wednesday, 12 June 2013 19:17:31 UTC