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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 11:05:22 +0100
Message-ID: <EMEW3|dac595cc3355a994c6931d78cf9adb98n6OB5P08L.Moreau|ecs.soton.ac.uk|4E2D3FE2.7090808@ecs.soton.ac.uk>
To: public-prov-wg@w3.org


On 07/25/2011 10:52 AM, Paul Groth wrote:
> Ok... and the justification for this is that it makes the data 
> structure uniform....?
Yes
>
> It seems that this unspecified role will have some kind of special 
> semantics, no?
>
It's a default role for asserters who don't assert a specific role.

Luc

> 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.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>
>

-- 
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 10:05:58 GMT

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