W3C home > Mailing lists > Public > public-rdf-shapes@w3.org > August 2014

Re: wording changes re normalization

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Thu, 07 Aug 2014 09:09:47 -0700
Message-ID: <53E3A4CB.4040200@gmail.com>
To: Jeremy J Carroll <jjc@syapse.com>, "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
Agreed.

I was hoping that this part of the WG work was going to be how to handle 
inferencing, but there was just a request for handling graph canonicalization 
in the WG.

So let me be more explicit.

RDF graph canonicalization has already been studied.  As Jeremy says, it is 
not an easy problem, due to blank nodes.   There is very little relationship 
between RDF graph canonicalization and RDF validation, so the WG should not be 
working on this.

peter


On 08/07/2014 07:13 AM, Jeremy J Carroll wrote:
> It is easy to forget that in general RDF canonicalization is Graph-Isomorphism
> complete, and hence too difficult for production use at scale. [1]
>
> On the other hand, within any particular application domain, which is the
> scope of the users of the proposed working group, normalizing an RDF graph
> tends to be fairly straightforward.
>
> Mindful of this I suggest:
>
> Section 1
> Replace;
> [[
> In addressing these issues, the WG will consider whether it is necessary,
> practical or desireable to normalize a graph prior to validation. That is,
> whether an algorithm can and should be defined that creates a canonical form
> of a given graph.
> ]]
> With
> [[
> In addressing these issues, the WG will consider whether it is necessary,
> practical or desireable to normalize a graph as part of validation. That is,
> whether an algorithm can and should be defined that creates a representation
> of a given graph, or an equivalent graph, that is canonical for the purpose of
> processing with respect to a specific machine-readable interface definition.
> ]]
>
> Rationale: the answer to the current question "should such an algorithm be
> defined" is simply "no, it should not"
> I weaken the question to indicate that the algorithm is part of validation,
> not prior, and that the canonicalization is not independent of the application
> but application dependent.
>
> Section 3:
> Replace:
> [[
> The WG *MAY* produce a Recommendation for *graph normalization*.
> ]]
> With
> [[
> 3. OPTIONAL - A graph normalization method, suitable for  the use cases
> determined by the group. This should not be a general purpose RDF
> canonicalization algorithm, see [1].
> ]]
> Rationale: consistent styling with other deliverables; restricting scope to
> avoid the impossible.
>
>
> [1]
> http://www.hpl.hp.com/techreports/2003/HPL-2003-142.pdf
>
>
Received on Thursday, 7 August 2014 16:10:18 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 17:02:40 UTC