Re: PROV-ISSUE-454 (key across relations/objectss): can the same identifier be used for different relations objects [prov-dm-constraints]

Hi all,

I tried to formulate a constraint to express this.

http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-constraints.html#key-relation2

Thoughts?

Luc
On 07/18/2012 10:57 AM, James Cheney wrote:
> HI,
>
> Again, I don't see the need for an explicit issue about this.
>
> There is currently no constraint enforcing disjointness among 
> different kinds of things/relations.  I see no particular reason to 
> add one (and make implementation harder), unless there is clear 
> consensus that violating such constraints is always nonsensical (and 
> that this isn't detected by other constraints).
>
> We (I thought) want to allow for the possibility that something is 
> both an agent and an entity, or both an agent or an activity, or other 
> combinations.  One could then state that something influences, 
> generates, uses itself etc., but this will just violate ordering 
> constraints that we already have.
>
> I agree it seems nonsensical to allow overlap between different 
> relations, and if so then someone needs to write constraints that do this.
>
> Constraints of the form "if hyp1 .... hypn then FALSE" (i.e., a given 
> conjunctive pattern is impossible" are straightforward to handle: we 
> just handle all the other inferences and constraints first, then check 
> that the normal form does not have any of the forbidden patterns. 
>  (The irreflexivity and asymmetry inferences for specialization 
> already do this implicitly.)
>
> --James
>
> On Jul 18, 2012, at 10:39 AM, Tom De Nies wrote:
>
>> The only problem I see with allowing it, is when using influencedBy.
>>
>> With influence you'd be allowed to assert this:
>>
>> agent(a1)
>> activity(a1)
>> influencedBy(a1,a1)
>>
>> - Tom
>>
>> 2012/7/18 Provenance Working Group Issue Tracker 
>> <sysbot+tracker@w3.org <mailto:sysbot+tracker@w3.org>>
>>
>>     PROV-ISSUE-454 (key across relations/objectss): can the  same
>>     identifier be used for  different relations objects
>>     [prov-dm-constraints]
>>
>>     http://www.w3.org/2011/prov/track/issues/454
>>
>>     Raised by: Luc Moreau
>>     On product: prov-dm-constraints
>>
>>
>>     We have the following two uniqueness constraints.
>>
>>     http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-constraints.html#key-object
>>     http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-constraints.html#key-relation
>>
>>     It is not clear to me if
>>
>>     entity(e123)
>>     agent(e123)
>>
>>     are acceptable. (To me, they should be, since we don't state the
>>     set of agents to be disjoint from any other set)
>>
>>     Likewise, can we write
>>
>>     used(event1234,a1,e1,attrs1)
>>     and
>>     wasGeneratedBy(event1234,e2,a2,attrs2)
>>
>>     Probably not.
>>     Note: if we allow the two above, then I am not sure that strict
>>     ordering is wise in ordering constraints.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.

-- 
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