Re: Constraint V Refinement

https://w3c.github.io/poe/model/01Constraint.png wanted to embed this
picture

On Fri, 8 Apr 2022 at 08:10, Simon Steyskal <simon.steyskal@gmail.com>
wrote:

> @victor
>
> >  I do not see a great difference between refinement or constraint
> because its interpretation is not defined (cf. examples in a testbed where
> an algorithm must behave differently in each case),
>
> well the idea was to make a distinction between (see discussion here
> https://github.com/w3c/poe/issues/282):
>
>    1. constraints that describe the world state under which a rule
>    becomes effective (Rule --odrl:constraint--> Constraint),
>    2. constraints that refine party/asset/action of a rule such that the
>    refined party/asset/action represents those affected by the Rule
>    (Action/AC/PC --odrl:refinement--> Constraint)
>
> [image: image.png]
>
> here are a few links to our discussions back in the day:
>
>    - https://github.com/w3c/poe/issues/211#issuecomment-325198929
>    - https://github.com/w3c/poe/issues/191#issuecomment-315283129
>    - https://github.com/w3c/poe/issues/112
>    - https://github.com/w3c/poe/issues/226 (discussion about refinements
>    at the end)
>
> > therefore the difference is only philosophical to me
>
> well, we explicitly prohibit outcomes of refinements to result in the
> empty set, see e.g.
>
>    - https://w3c.github.io/poe/model/#constraint-action
>       - Note: The outcome of applying refinements to an Action SHOULD NOT
>       result in a null operation.
>    - https://w3c.github.io/poe/model/#constraint-asset
>    - Note: The outcome of applying refinements to an AssetCollection
>       SHOULD NOT result in a null set.
>
> while this comes with its own slew of issues, restrictions that for
> example can't be satisfied at all can technically not be used as refinements
>
> > Can someone suggest improved definitions/clarifications for these:
> >  - A Rule MAY include the constraint property to indicate a condition on
> the Rule.
> >  - An Action MAY include the refinement property to indicate a
> Constraint that narrows the semantics of the Action operation directly.
>
> but not for:
> - An AssetCollection MAY include a refinement property to indicate the
> refinement context under which to identify individual Asset(s) of the
> complete collection.
> - A PartyCollection MAY include a refinement property to indicate the
> refinement context under which to identify individual Party(ies) of the
> complete collection.
> ?
>
> Btw in the BP document, deliveryChannel is used as refinement on the
> action
> https://w3c.github.io/odrl/bp/#x2-1-narrowing-the-applicability-of-an-action
>
> cheers, simon
>
> On Fri, 8 Apr 2022 at 07:33, Renato Iannella <r@iannel.la> wrote:
>
>> I think we need to provide guidance on the difference.
>>
>> Otherwise, different implementations may use deliveryChannel as an action
>> refinement  in one Policy, then as a rule constraint in another.
>> (this would be good content for the Best Practices guide:
>> https://w3c.github.io/odrl/bp/)
>>
>> Can someone suggest improved definitions/clarifications for these:
>>   - A Rule MAY include the constraint property to indicate a condition on
>> the Rule.
>>   - An Action MAY include the refinement property to indicate a
>> Constraint that narrows the semantics of the Action operation directly.
>>
>> Cheers - Renato
>>
>>
>> On 8 Apr 2022, at 00:20, Víctor Rodríguez Doncel <vrodriguez@fi.upm.es>
>> wrote:
>>
>> Hi,
>>
>> I do not see a great difference between refinement or constraint because
>> its interpretation is not defined (cf. examples in a testbed where an
>> algorithm must behave differently in each case), therefore the difference
>> is only philosophical to me. And even in this case unclear: I would have
>> said constraint, though, for the deliveryChannel, and if refinement,
>> refinement of the action (this would be like an "adverb" modifying the
>> action rather than an "adjective" qualifying the asset)
>>
>> Regards,
>> Víctor
>>
>> > Is the deliveryChannel a refinement on ‘stream’ or a constraint on the
>> rule?
>>
>> refinement on the asset i.e. the video itself? e.g., => "you can stream
>> (action) videos whose deliveryChannel is YouTube (asset with
>> deliveryChannel == YT)
>>
>> br, simon
>>
>>
>> On Thu, 7 Apr 2022 at 02:42, Renato Iannella <r@iannel.la> wrote:
>>
>>>
>>> Hi all, we generally define the constraint property as a “condition on
>>> the rule” and the refinement property as “narrow the semantics of the
>>> action”.
>>>
>>> So, for example temporal and geospatial conditions apply to the rule,
>>> and printing at most 5 times is a refinement to print.
>>>
>>> My question is how to interpret this difference with other use cases,
>>> such as:
>>>  - you can stream (action) a video (asset)  on YouTube (deliveryChannel)
>>> only?
>>>
>>> Is the deliveryChannel a refinement on ‘stream’ or a constraint on the
>>> rule?
>>>
>>> Thanks…Renato
>>>
>>
>>
>> --
>> Víctor Rodríguez-Doncel
>> D3205 - Ontology Engineering Group (OEG)
>> Departamento de Inteligencia Artificial
>> ETS de Ingenieros Informáticos
>> Universidad Politécnica de Madrid
>>
>> Campus de Montegancedo s/n
>> Boadilla del Monte-28660 Madrid, Spain
>> Tel. (+34) 910672914
>> Skype: vroddon3http://cosasbuenas.es
>>
>>
>>
>>