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Re: Literals as subjects in Turtle (but not in the RDF model) [was: Inverses of RDF and RDFS predicates]

From: David Booth <david@dbooth.org>
Date: Fri, 04 May 2012 09:13:50 -0400
To: Sandro Hawke <sandro@w3.org>
Cc: nathan@webr3.org, Ivan Herman <ivan@w3.org>, David Wood <david@3roundstones.com>, Richard Cyganiak <richard@cyganiak.de>, "public-rdf-comments@w3.org" <public-rdf-comments@w3.org>
Message-ID: <1336137230.2232.24424.camel@dbooth-laptop>
On Thu, 2012-05-03 at 17:40 -0400, Sandro Hawke wrote:
[ . . . ]
> What I understood several people to say at the RDF Next Steps Workshop,
> and on the mailing lists after it, was that their RDF systems were not
> like this.  They said their systems could not handle literals in the
> subject position without a more re-working than they were willing to do.
> They claimed it was not a simple matter of removing a restriction.  As I
> recall, these were some of the major RDF product suppliers and/or users,
> so it seemed to make sense to listen.

Yes, as I recall that was the major objection.  A minor objection was
that it would allow a user to write "bad" RDF like:

  "Alice" foaf:knows "Bob" .

But that was two years ago, and tools are evolving.  I would hope that
newer tools would be designed to at least have an option to allow
literals as subjects.

In fact, I think it would be helpful for the WG to put tool makers on
notice that this restriction is likely to be removed at some point in
the future, and they should plan accordingly.  Otherwise, we would
forever be stuck in a circular situation similar to what Nathan pointed
out, that we can't remove this restriction from the tools because it's
in the RDF standard, and we can't remove it from the RDF standard
because it's in the tools.

In the very least, it is clear that there is a significant market of
users who do not want this restriction, and tool makers would be wise to
make this restriction optional.

BTW, this restriction is not just "silly" in an
aesthetically-displeasing-but-harmless kind of way.  It is *harmful*,
because it prevents certain things from being modeled in the way that
they *should* be modeled (i.e., in the simplest, most direct way), and
it forces applications to be more complex because they *cannot* treat
subjects and objects uniformly and treat properties as uniformly
invertable.


-- 
David Booth, Ph.D.
http://dbooth.org/

Opinions expressed herein are those of the author and do not necessarily
reflect those of his employer.
Received on Friday, 4 May 2012 13:14:25 GMT

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