W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > September 2002

Re: handling bare literals and PS a Q. about lang tags

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Fri, 06 Sep 2002 12:07:40 +0100
To: pat hayes <phayes@ai.uwf.edu>
cc: w3c-rdfcore-wg@w3.org
Message-ID: <17069.1031310460@hoth.ilrt.bris.ac.uk>

>>>pat hayes said:

<snip/>

> Finally, one alternative is to do all the above but ALSO allow bare 
> literals as legal nodes, and require them to follow Dan's preferences 
> and denote themselves. Then *bare* literals provide a way to refer to 
> lexical forms, and datatyped literals (including those with bnodes in 
> them) allow us to use literals to refer to values. In this case all 
> nodes would be tidy also, but a bare literal would never be the same 
> as a literal node.  In many ways this conforms to everyone's wishes, 
> I think: literals always refer to themselves, datatyped literal nodes 
> always refer to values, all the usual semantic rules apply uniformly, 
> and we can say anything. The only real cost will be to legacy systems 
> which use bare literals to refer to values, but they will need to be 
> changed, probably, whatever we do. And we can discuss the translation 
> strategies in the previous paragraph, with their pros and cons, for 
> use by conversion implementers.

I'm not clear what you are saying here with "legacy systems which use
bare literals to refer to values".  Are you saying:

  <foo:prop>10</foo:prop>

would give different triples?

ie not
  _:a <http://example.org#prop> "10"
but something else:
  _:a <http://example.org#prop> _:b"10"

I can't yet work out how large the impact is of making all literal
nodes be a (basic node, literal) pair.  This obviously affects
N-Triples but I think it also changes all our test cases and every
piece of rdf code ever written.  Or am I misreading something?

I guess if as you suggested after Connolly [[ use the same bnode for
every literal in the entire world]] that would reduce the pain since
existing systems would implicitly be using that.


I'm also not sure if you haven't sort-of sneaked in literal subjects
which was a postponed issue:

[[
we are able to say things like

Jenny ex:age (_:y, "10") .
_:y rdf:type rdf:Datatype .
]]

The above isn't representable in RDF/XML (with datatypes attribute)
unless we add another one: rdf:datatypeNodeID

Dave
Received on Friday, 6 September 2002 07:10:02 EDT

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