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Re: Provenance model, syntax and formal properties

From: Graham Klyne <graham.klyne@zoo.ox.ac.uk>
Date: Fri, 24 Feb 2012 07:02:22 +0000
Message-ID: <4F4735FE.8020903@zoo.ox.ac.uk>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
CC: W3C provenance WG <public-prov-wg@w3.org>
On 24/02/2012 06:26, Luc Moreau wrote:
> Hi Graham
> A quick answer to two of your points;
> - the ASN acronym has been bothering me for a while.
>    Indeed, it's a notation, not an abstract syntax.
>    I am open to suggestion, I suggest I raise an issue to debate the name.
> - we received feedback on two occasions that the grammar of the AsN is a hurdle for readers.
>    I think it's right to separate terms definitions from grammar.
>    Yesterday, we left it open to editors to create two documents, eg ASN in appendix to DM. We don't need to finalise a decision now.

Hmmmm... In my experience, developers are quite adept at reading and 
interpreting syntax productions.

I can't help wondering if the reported problem was due not so much the syntax 
definition itself, but the fact that its presentation was bound up with a lot of 
the other complexities that we are separating out.  Also, presenting it as an 
abstraction rather than a convenience notation might exacerbate that effect?

Having it as an appendix in Part 1 could be a reasonable compromise, especially 
if each element description is hyperlinked to the syntax production in the 
appendix (e.g. in sect 4.1.1, where you have "written entity(id, ...)").

>    The challenge as you say is to make sure that the Asn is explained enough in prov-dm to read examples.  We did it in the original document: a full example before the grammar.

Actually, I did not find that helpful (a) the example presented too much both 
conceptual and syntactic material to be understood all-at-once, and (b) the 
example did not describe the syntax, it used it.  I find helpful examples are 
those that are introduced to illustrate or illuminate a proximal technical issue.


> Professor Luc Moreau
> Electronics and Computer Science
> University of Southampton
> Southampton SO17 1BJ
> United Kingdom
> On 24 Feb 2012, at 05:55, "Graham Klyne"<graham.klyne@zoo.ox.ac.uk>  wrote:
>> I've been thinking about my review yesterday of the "wrong" PROV-DM WD4 document, and my subsequent scan of the newer version of Part 1, which leads me to question whether we've got the right breakdown.
>> TL;DR: consider a breakdown of provenance model into just two parts:
>> (1) provenance model, covering concepts model and functional notation syntax
>> (2) formal properties, covering assumed constraints and inferences and provenance of changeable things
>> ...
>> I realize that in yesterday's telecon, we resolved to split the document into three parts, but in the light of a better understanding of what we're defining and what we're proposing, I want to reopen the question whether we've chosen the right breakdown.  I also have some concerns about terminology.
>> I probably missed something, but my original expectation following the F2F was that the DM document would be separated into *two* parts: one providing a concise description of the model and the concepts, and the second dealing with its formal properties.  What I think we agreed yesterday was *three* parts: the "model", "constraints" and "abstract syntax".
>> First the  terminology:
>> I don't think the terms "abstract syntax" and  "constraints" are quite right. The "abstract syntax" is not really an abstract syntax, but a concrete syntax for a functional notation for provenance - so why don't we call it a "functional notation" (like OWL has)?
>> My other problem is the characterization of the formal properties as "constraints";  it's true that the inferences that we want provenance to support come about because of the constraints the expressions are assumed to obey, but to characterize the whole topic as "constraints" is, I think to miss the main point.  I think what we're really describing is a provenance algebra.
>> And so to the substantive matter of how to make the required simplifications:
>> Reflecting on my review of the older DM document, none of the problems of difficulty or complexity that I encountered were to do with the syntax.
>> Indeed, I think that, in many ways, the syntax actually helps to make clear what are the constituents of each provenance record, as long as it's handled in a way that doesn't get bogged down in lexical minutiae, in which I think the original handling of syntax did quite well.  Further, the functional notation syntax gives us a concise notation for talking about provenance records, and in particular for presenting examples.  It seems strange to me that the proposed "Part 1" document contains examples that use the syntax without actually defining it.  I think the syntax productions could be included in the new PROV-DM core section without significantly complicating it.
>> So my suggestion is to consider a breakdown into *two* parts:
>> (1) provenance model, covering concepts model and functional notation syntax
>> (2) provenance algebra, or formal properties, covering assumed constraints and inferences, and in particular opening up the issues of how to handle provenance for dynamic resources.  The formal properties described here are underpinned by the formal semantics (model theory) document.
>> #g
Received on Friday, 24 February 2012 07:04:41 UTC

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