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Re: Subjects as Literals, [was Re: The Ordered List Ontology]

From: Ivan Mikhailov <imikhailov@openlinksw.com>
Date: Fri, 02 Jul 2010 11:50:32 +0700
To: Yves Raimond <yves.raimond@gmail.com>
Cc: Kingsley Idehen <kidehen@openlinksw.com>, Henry Story <henry.story@gmail.com>, nathan@webr3.org, Pat Hayes <phayes@ihmc.us>, Toby Inkster <tai@g5n.co.uk>, Dan Brickley <danbri@danbri.org>, Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
Message-ID: <1278046232.11759.346.camel@octo.iv.dev.null>
Hello Yves,

> > It's a virtuoso function surfaced as a predicate.
> > "magic predicate" was an initial moniker used at creation time.
> > "bif:contains" doesn't exist in pure triple form etc..
> 
> Why couldn't it? For example, you may want to express exactly what
> triple lead you to give a particular result, and within that scope you
> may end up having to write: "Brickley" bif:contains "ckley" in RDF.
> 
> Forbidding literals as subjects makes this statement impossible to
> express, however that's a very sensible thing you may want to express.
> 
> There are also lots of literal search examples that comes to mind:
> 
> "Acton" str:double_metaphone "AKTN" .
> "Smith" str:soundex "S530" .

Yes, SPARQL permits literals in subject position, and we use that for
dirty hacks. That does not mean that raw data should permit the same.
SPARQL (and especially our SPARQL/BI) uses many different things in
subject position, e.g., variables (and expressions, up to subqueries)
that's not an excuse to allow the same in raw data.

I don't even say about technical price of the extension for both
developers (extra work) and each user of any big RDF storage (extra
hardware). I simply don't see a reason, because literals are simply
_not_enough_unique_ to interlink data.

[ ] str:double_metaphone_word "Acton" ; str:double_metaphone "AKTN" .
and
[ ] str:soundex_word "Smith" ; str:soundex "S530" .

are at least protected from collisions and allow more properties to be added in a safe way.


Best Regards,

Ivan Mikhailov
OpenLink Software
http://virtuoso.openlinksw.com
Received on Friday, 2 July 2010 04:52:40 UTC

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