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Re: URI Comparisons: RFC 2616 vs. RDF

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Tue, 18 Jan 2011 22:55:39 -0500
Message-ID: <AANLkTimB2ohim=4g6EmdhizY-G2AKSMnm6Hg2auCe2yg@mail.gmail.com>
To: Dave Reynolds <dave.e.reynolds@gmail.com>
Cc: nathan@webr3.org, public-lod@w3.org
On Tue, Jan 18, 2011 at 3:47 AM, Dave Reynolds
<dave.e.reynolds@gmail.com> wrote:
>> As for RIF and GRDDL, can anybody point me to the reasons why
>> normalization are not performed, does this have xmlns heritage?
>
> Not as far as I know. At least in RIF we were just trying to b
> compatible with the RDF specs which (cwm not withstanding) do not
> specify normalization other than the IRI-compatible character encoding.
>

Similarly OWL. OWL says, following the sense of the anticipation of
the IRI spec: "Two IRIs are structurally equivalent if and only if
their string representations are identical."

As far as I can tell, you (Dave) are the only person in this
conversation who cites the specification relevant to answering the
question posed.  That specification makes clear, as you have cited,
exactly how RDF interpreters are to compare URI references.

The information on how to fully determine equivalence according to the
URI spec is distributed across a wide and growing number of different
specifications (because it is schema dependent) and could, in
principle, change over time. Because of the distributed nature of the
information it is not feasible to fully implement these rules.
Optionally implementing these rules (each implementor choosing where
on the ladder they want to be) would mean that documents written in
RDF (and derivative languages) would be interpreted differently by
different implementations, which is an unacceptable feature of
languages designed for unambiguous communication. The fact that the
set of rules is growing and possibly changing would lead to a similar
situation - documents that meant one thing at one time could mean
different things later, which is also unacceptable, for the same
reason.

David (Wood) clarifies (surprisingly to me as well) that the issue of
normalization could be addressed by the working group. I expect,
however, that any proposed change would quickly be determined to be
counter to the instructions given in the charter on Compatibility and
Deployment Expectation, and if not, would be rejected after justified
objections on this basis from reviewers outside the working group.

-Alan
Received on Wednesday, 19 January 2011 03:56:28 UTC

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