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Re: PROV-ISSUE-40 (recommended-roles): Roles should not be SHOULD and not MUST [Conceptual Model]

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Mon, 25 Jul 2011 10:51:20 +0100
Message-ID: <EMEW3|57dcc4a6b3dce6d160f636dad49e61d3n6OApN08L.Moreau|ecs.soton.ac.uk|4E2D3C98.4030907@ecs.soton.ac.uk>
To: Paul Groth <p.t.groth@vu.nl>
CC: "public-prov-wg@w3.org" <public-prov-wg@w3.org>
Remember that I suggested concrete representations have the opportunity to
offer role-less convenience syntax (as a kind of "macro" that expands 
into a construct
with a role "unspecified").

Using the notation in the spec:
   use(pe,e)  expands to use(pe,e,unspecifiedRole)
where unspecifiedRole is a distinguished role.

Isn't your requirement about "easy writing"? I believe an appropriate
choice of syntax addresses this requirement.


On 07/25/2011 10:35 AM, Paul Groth wrote:
> I'm using the definitions in [1], which are used in W3C specs. The 
> definitions for MUST and SHOULD are:
> - MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the
>    definition is an absolute requirement of the specification.
> - SHOULD   This word, or the adjective "RECOMMENDED", mean that there
>    may exist valid reasons in particular circumstances to ignore a
>    particular item, but the full implications must be understood and
>    carefully weighed before choosing a different course.
> The justification for using SHOULD is that it allows me some 
> flexibility in writing down provenance that is compatible with the 
> spec. If I don't know the roles and I won't break anything but I might 
> not get the full functionality of the spec (maybe?). So I think that 
> there are valid reasons not to write down roles but probably I should 
> think before not doing it.
> cheers,
> Paul
> [1] http://www.ietf.org/rfc/rfc2119.txt
> Luc Moreau wrote:
>> It would be good to have advise on the choice MUST/SHOULD.
>> I would have thought that to promote interoperability we should go for
>> the stronger requirements,
>> when possible.
>> I can turn your comment around. I'm missing a justification for a SHOULD
>> here.
>> Luc
>> PS. I don't think it's a hack to have unspecified role. Mandating a role
>> guarantees a uniform data structure.
>>       It facilitates the writing of queries/searches.  I guess that's my
>> justification for MUST.
>> On 07/25/2011 10:22 AM, Paul Groth wrote:
>>> It seems like unspecified is a hack to let you get around not saying a
>>> role.
>>> Again, I think I'm missing a justification of the MUST verses just
>>> making it a strong recommendation (i.e. SHOULD).
>>> I think you have some inferences in mind based around roles.... but I
>>> think it just means that you won't be able to make those inferences if
>>> you don't provide roles.
>>> thanks,
>>> Paul
>>> Luc Moreau wrote:
>>>> I believe there is a difference between a conceptual model and its
>>>> encoding in
>>>> a specific data/knowledge format.
>>>> In my view, it is reasonable to require the presence of a role in a
>>>> conceptual model.
>>>> A given notation, say RDF, may provide "abbreviations", which allow 
>>>> for
>>>> the role not
>>>> to be expressed. This notation will have an explanation that 
>>>> absence of
>>>> a role corresponds
>>>> to the role  "unspecified".
>>>> So, I believe that the conceptual model should define distinguished
>>>> roles, e.g. unspecified.
>>>> BTW, the file note.txt in the repository also suggested other roles
>>>> Luc
>>>> On 07/23/2011 03:14 PM, Provenance Working Group Issue Tracker wrote:
>>>>> PROV-ISSUE-40 (recommended-roles): Roles should not be SHOULD and
>>>>> not MUST [Conceptual Model]
>>>>> http://www.w3.org/2011/prov/track/issues/40
>>>>> Raised by: Paul Groth
>>>>> On product: Conceptual Model
>>>>> Currently, roles are required for Generation, Use, and 
>>>>> isControlledby.
>>>>> Specifically the following sentence is given:
>>>>> "Use, Generation, and Control assertions must contain a role."
>>>>> It is not clear why roles must always be there. In some cases, I may
>>>>> not want to assert the role that something played with respect to a
>>>>> process.
>>>>> Suggested resolution is to replace MUST with SHOULD.

Professor Luc Moreau
Electronics and Computer Science   tel:   +44 23 8059 4487
University of Southampton          fax:   +44 23 8059 2865
Southampton SO17 1BJ               email: l.moreau@ecs.soton.ac.uk
United Kingdom                     http://www.ecs.soton.ac.uk/~lavm
Received on Monday, 25 July 2011 09:52:05 UTC

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