W3C home > Mailing lists > Public > public-prov-wg@w3.org > April 2012

Re: PROV-ISSUE-333 - feedback on PROV-CONSTRAINTS

From: Paul Groth <p.t.groth@vu.nl>
Date: Mon, 9 Apr 2012 15:58:28 +0200
Message-ID: <CAJCyKRqHq7bwf1qW-pmdqwdWU=cooc_OA5te4gZbpk3rVGndCA@mail.gmail.com>
To: Graham Klyne <graham.klyne@zoo.ox.ac.uk>
Cc: W3C provenance WG <public-prov-wg@w3.org>
Hi Graham,

I think it would be useful if you continue the review of the
constraints. Otherwise, we do not know where we sit with respect to
the whole of the document. I think the constraints can be reviewed as
to whether they are correct or not.

regards
Paul

On Sun, Apr 8, 2012 at 11:19 PM, Graham Klyne <graham.klyne@zoo.ox.ac.uk> wrote:
> Summary:  not ready for release.  Sorry!
>
> I've read this document up to section 2.2 and, based on what I've read, I'm not
> sure I can see any reason for this document to exist.
>
> When we set out on this path of separating the description of constrained (or
> "strict") provenance from "scruffy" provenance, my understanding was that:
> (1) we wished to provide an easy-to-understand provenance data model that anyone
> could use to generate and present provenance information, and
> (2) we wished to describe a strict, or constrained, use of this model that would
> allow certain conclusions to be validly inferred.
>
> As such, the PROV-CONSTRAINTS document needs to build upon the PROV-DM document
> in a way that doesn't seek to invalidate things that people do based on PROV-DM
> alone (cf. Paul's use-case about making provenance statements about his blog).
>
> Yet this is not what I see when I read the PROV-CONSTRAINTS document.  What I
> see is a document that (a) simply repeats a lot of material that is present in
> PROV-DM (I think familiarity with the contents of PROV-DM should be assumed for
> readers of PROV-CONSTRAINTS), and (b) introduces new definitions that seem to
> invalidate some usage that would be valid based on a reading of PROV-DM alone
> (e.g. the MUST constraint in section 2.1.2, para 3).  I think it is important
> that PROV-CONSTRAINTS MUST NOT invalidate a naive use of the provenance model.
> In this light, I find several parts of the text I have read to be contradictory
> (e.g. section 2.1 paras 3 & 4, or the notion that "event" underpins PROV-DM when
> it isn't even mentioned there).
>
> The goal, as I understand it, is that when provenance statements are made in a
> way that conform to the stricter usage, then certain inferences become valid.
>
> In writing this, I realize that there is something that, to my knowledge, has
> not been discussed in the WG.  If presented with some arbitrary provenance
> information, how is an agent to know if it has been constructed with regard to
> the strict constraints of PROV-CONSTRAINTS, or is simply a looser use of the
> basic provenance model?  Without some way to answer this, I think the "scruffy"
> and "strict" (for want of more evocative terms) approaches to expressing
> provenance are destined to flounder.
>
> So, for this document to work as I understand it is intended to do, I think it
> needs:
> (1) to start out with a much clearer articulation of its goal - I find the
> present section 1 introduction tells me nothing that I actually need to know
> about the role of PROV-CONSTRAINTS, and
> (2) we need a way to recognize when provenance statements are intended to be
> interpreted according to the strict usage defined by PROV-CONSTRAINTS.
>
> For (1), stripping out the introductory references and repetition of PROV-DM, I
> think something like this is needed:
>
> [[
> This specification defines a strict, or constrained, usage of the provenance
> data model which, if followed, makes a number of conclusions commonly drawn from
> provenance information to be logically valid inferences.  It also defines a way
> to assert that the provenance usage conforms to this strict usage.  These
> constraints are also reflected in the provenance formal semantics [@@ref].
> ]]
>
> For (2), I don't have any definite proposal, though I can imagine some
> approaches.  The following are intended as seeds of ideas, not definite suggestions:
> * a subproperty of prov:hasProvenance, e.g. prov:hasStrictProvenance, that
> relates provenance to some entity.
> * a property associated with a prov:Account that indicates that the provenance
> statements in that account can be interpreted as strict provenance
> * a property of an agent or activity associated with generation a provenance
> account that indicates that the generation process follows strict provenance
> constraints in generating provenance statements.
> * etc.
>
> Until these fundamental issues are addressed, I think that any further comment
> on the content of this document would be in the league of shuffling deckchairs
> on the Titanic.
>
> #g
>
>



-- 
--
Dr. Paul Groth (p.t.groth@vu.nl)
http://www.few.vu.nl/~pgroth/
Assistant Professor
Knowledge Representation & Reasoning Group
Artificial Intelligence Section
Department of Computer Science
VU University Amsterdam
Received on Monday, 9 April 2012 13:58:58 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 26 April 2012 13:07:03 GMT