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Re: PROV-ISSUE-105: 5.3.1 Generation (current version of the conceptual model document) [Conceptual Model]

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Wed, 30 Nov 2011 12:17:32 +0000
Message-ID: <EMEW3|93fc5529b2f5aa4eea422cf841b2ee22nAYCHZ08L.Moreau|ecs.soton.ac.uk|4ED61EDC.6050509@ecs.soton.ac.uk>
To: public-prov-wg@w3.org
Hi Satya,

Can you confirm you are satisfied with the way this issue was addressed?
We would like to close it formally.


On 11/07/2011 11:29 AM, Luc Moreau wrote:
> Hi Satya,
> Responses interleaved.   I am also proposing to close this issue.
> On 09/28/2011 05:16 PM, Provenance Working Group Issue Tracker wrote:
>> PROV-ISSUE-105: 5.3.1 Generation (current version of the conceptual 
>> model document) [Conceptual Model]
>> http://www.w3.org/2011/prov/track/issues/105
>> Raised by: Satya Sahoo
>> On product: Conceptual Model
>> Hi,
>> My review comments for 5.3.1 Generation in the current version of the 
>> conceptual model document:
>> 5.3.1 Generation
>> =====
>> 1. In PROV-DM, a generation expression is a representation of a world 
>> event, the creation of a new characterized thing by an activity. This 
>> characterized thing did not exist before creation.
>> Issue: The "characterized thing" in the above statements is Entity or 
>> some other resource?
> Now,  we have defined entity as an identifiable characterized thing. 
> So, the statements has become:
> In PROV-DM, a generation record is a representation of a world event, 
> the creation of a new entity by an activity. This entity did not exist 
> before creation. The representation of this event encompasses a 
> description of the modalities of generation of this entity by this 
> activity.
>> 2. contains a generationQualifier q that describes the modalities of 
>> generation of this thing by this activity
>> Issue: How is this qualifier distinct from specialization of the 
>> generation property?
> I think the work on prov-o now answers this question.
>> 3. The first one is available as the first value on port p1, whereas 
>> the other is the second value on port p1.
>> Issue: As we discussed during the telcon on  Sept 15 [1] and in email 
>> thread (Subject: Roles, initiated by Paolo on Sept 15), the 
>> "qualifier" if any are on the entity and PE and not on the relation. 
>> In the above statement, port p1 is qualifier for either the entities 
>> e1, e2 (they were generated on that particular port) or the PE pe1 
>> (it was using that port for listening/responding). Hence, the 
>> qualifiers are on the "class" and not the "relation".
>> [1] http://www.w3.org/2011/prov/meeting/2011-09-15
> I think the work on prov-o also answers this comment.
>> 4. If two process executions sequentially set different values to 
>> some attribute by means of two different generate events, then they 
>> generate distinct entities.
>> Issue: This is an incorrect statement. Setting values of an entity at 
>> different points of time cannot be equated to generating new 
>> entities. For example, we don't generate a new human being everytime 
>> a PE changes the value of their age. pe1 sets Person X age = 5 years 
>> in 2005 and pe2 sets Person X age = 10 years in 2010 then they are 
>> not generating new person (within an account or across accounts).
> Remember that an entity is a perspective on a thing.
> So, here, we can have multiple perspectives:
> e1 Luc
> e2 Luc at age=5
> e3 Luc at age=10
> e3 and e2 have a same attribute name age, but different values. So 
> they must be different entities,i.e. perspectives, over human being e1.
>> 5. Alternatively, for two process executions to generate an entity 
>> simultaneously, they would require some synchronization by which they 
>> agree the entity is released for use; the end of this synchronization 
>> would constitute the actual generation of the entity, but is 
>> performed by a single process execution.Given an entity expression 
>> denoted by e, two process execution expressions denoted by pe1 and 
>> pe2, and two qualifiers q1 and q2, if the expressions 
>> wasGeneratedBy(e,pe1,q1) and wasGeneratedBy(e,pe2,q2) exist in the 
>> scope of a given account, then pe1=pe2 and q1=q2.
>> Issue: If two sculptors collaborate on creating a human figurine 
>> statue entity e1: sculptor A by PE pe1 creates the arms and legs of 
>> e1 and sculptor B by PE pe2 creates the head and upper-body part of 
>> e1 then both pe1 and pe2 create e1. They may or may not be 
>> synchronized. How can we infer that pe1 = pe2 (whether in one account 
>> or across accounts)?
> I think you've articulated well the case that A and B create different 
> parts.  If they do this at different times, you will have
> statue without head, statue with head without leg, statue with head 
> with leg.
> The constrained with accounts on generation-unicity is enforcing some 
> structure in the provenance records, so that if really pe1<>pe2, then
> they should generate the statue in different records.
> I am proposing, in the end, to follow Simon's proposal, and move this 
> in an entirely different section.
>> 6. Given an identifier pe for a process execution expression, an 
>> identifier e for an entity expression, qualifier q, and optional time 
>> t, if the assertion wasGeneratedBy(e,pe,r) or 
>> wasGeneratedBy(e,pe,r,t) holds, then the values of some of e's 
>> attributes are determined by the activity represented by process 
>> execution expression identified by pe and the entity expressions used 
>> by pe. Only some (possibly none) of the attributes values may be 
>> determined since, in an open world, not all used entity expressions 
>> may have been asserted. [PROV:0002]
>> Issue: This constraint is confusing (maybe even contradictory) - some 
>> or none attributes may be determined? Further, there is no 
>> specification or mechanism defined to identify which attributes were 
>> determined by the PE? the constraint does not provide any new 
>> information (even as a constraint) regarding generation.
> We have decided to drop this constraint at the last teleconference.
>> 7. If an assertion wasGeneratedBy(x,pe,r) or 
>> wasGeneratedBy(x,pe,r,t), then generation of the thing denoted by x 
>> precedes the end of pe and follows the beginning of pe.
>> Issue: Suggest rewording this: given the assertion that "an Entity e1 
>> was generated by a PE pe1" then "the Entity e1 did not exist before 
>> start of PE pe1".
> This would be an entirely different meaning that is not the same as 
> the one intended.
> Cheers,
> Luc

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 Wednesday, 30 November 2011 12:19:11 UTC

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