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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 
uniform....?

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

Paul

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)
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, 25 July 2011 09:55:23 GMT

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