Re: PROV-ISSUE-458: wasInfluencedBy is not irreflexive [prov-dm-constraints]

Luc, James,

On Jul 20, 2012, at 6:55 AM, James Cheney wrote:

> I added the irreflexivity constraint directly to address concerns raised in discussion by Tim and Tom on issue 454.  I haven't heard whether this proposed fix, or Luc's example of a reflexive communication, addresses their concern.
> 
> Briefly, I think wasInformedBy(a,a) is a bug,

+1


> and we should fix it by dropping generation-use-communication, and keeping influence irreflexive.  However, I'm not going to fight for irreflexive influence if Luc's example convinces everyone else that it may be reflexive.


1)

prov-constraints is available to distinguish proper provenance from the scruffy provenance that prov-dm permits.
A distinguishing characteristic between proper and scruffy is "precision"; The former has it, and the latter need not.

The statement:

      wasInformedBy(a,a) 

is hardly precise, and without some precision it is not informative. 
Why would one inform oneself? Didn't the one already know it? 
You're implying two parts of oneself, and should thus distinguish them, describe them separately, and relate them appropriately.

Meanwhile, it seems like a perfectly reasonable prov-dm statement.

The same argument applies to the general property wasInfluencedBy.


2)

In a different topic but related to precision, does the latest prov-constraints prevent:

:e prov:wasGeneratedBy :a_1, :a_2 .
:a_1 owl:differentFrom :a_2 .


Thanks,
Tim



> 
> I am copying my comments from issue 454 for easy reference:
>> The irreflexivity constraint was an attempt to address Tim and Tom's concerns, so they should comment on whether your example persuades them that it is not irreflexive.
>> 
>> My inclination would be that influence and communication should be irreflexive, so this is no problem.  
>> 
>> But if we also allow the generation-use-communication inference, then from the totally reasonable:
>> 
>> wasGeneratedBy(e,a)
>> used(a,e)
>> 
>> we could infer wasInformedBy(a,a) and then wasInfluencedBy(a,a), which would be invalid if influence has to be irreflexive.
>> 
>> Overall, I think this makes a persuasive argument for dropping generation-use-communication and keeping irreflexivity of influence (and all this entails).
> 
> --James
> 
> On Jul 20, 2012, at 9:07 AM, Provenance Working Group Issue Tracker wrote:
> 
>> PROV-ISSUE-458: wasInfluencedBy is not irreflexive  [prov-dm-constraints]
>> 
>> http://www.w3.org/2011/prov/track/issues/458
>> 
>> Raised by: Luc Moreau
>> On product: prov-dm-constraints
>> 
>> Going back to the definition in prov-dm,
>> 
>> Communication is the exchange of some unspecified entity by two activities, one activity using some entity generated by the other.
>> 
>> I can imagine a service invoking itself (so effectively, exchanging an entity with itself).
>> 
>> So, it would  be fine to write:
>> 
>> wasInformedBy(a,a)   
>> 
>> Therefore, 
>> 
>> wasInfluencedBy(a,a)
>> 
>> which contradicts the constraints:
>> 
>> http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-constraints.html#impossible-influence-reflexive
>> 
>> 
>> 
>> 
>> 
>> 
>> 
> 
> 
> -- 
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
> 
> 
>

Received on Monday, 23 July 2012 12:47:53 UTC