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

From: Paul Groth <p.t.groth@vu.nl>
Date: Mon, 25 Jul 2011 11:52:38 +0200
Message-ID: <4E2D3CE6.3080205@vu.nl>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
CC: "public-prov-wg@w3.org" <public-prov-wg@w3.org>
Ok... and the justification for this is that it makes the data structure 

It seems that this unspecified role will have some kind of special 
semantics, no?


Luc Moreau wrote:
> 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.
> Luc
> 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.

Dr. Paul Groth (p.t.groth@vu.nl)
Assistant Professor
Knowledge Representation & Reasoning Group
Artificial Intelligence Section
Department of Computer Science
VU University Amsterdam
Received on Monday, 25 July 2011 09:55:23 UTC

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