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Re: PROV-ISSUE-43 (derivation-time): Deriviation should have associated time [Conceptual Model]

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Wed, 27 Jul 2011 15:44:23 +0100
Message-ID: <EMEW3|6d956da9d582832055c09be82934b516n6QFiY08L.Moreau|ecs.soton.ac.uk|4E302447.4020206@ecs.soton.ac.uk>
To: public-prov-wg@w3.org

Hi,

The latest version of the document includes a new section that relates
derivation to process execution [1]. I copy the text here for convenience.
Note that this does not directly resolves this issue, but it provides us 
with
a basis to discuss time in the context of derivation.


5.5.1 Relationship between derivation and process execution

A derivation, which by definition expresses that some characterized 
entity is transformed from, created from, or affected by another 
characterized entity, entails a process execution that transforms, 
creates or affects this characterized entity.

This is formalized by the following inference rule, referred to as 
process execution introduction:
if isDerivedFrom(e1,e0) holds, then there exists a process execution pe, 
and roles r0,r1, such that: isGeneratedBy(e1,pe,r1) and uses(pe,e0,r0).

The converse inference does not hold. Indeed, when a generation 
isGeneratedBy(e1,pe,r1) precedes uses(pe,e0,r0), for some e0, e1, r0, 
r1, and pe, one cannot infer derivation isDerivedFrom(e1,e0) since the 
values of attributes of e1 cannot possibly be determined by the values 
of attributes of e0, given the creation of e1 precedes the use of e0.

Cheers,

Paolo and Luc


[1] 
http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#relationship-between-derivation-and-process-execution

On 07/27/2011 09:11 AM, Khalid Belhajjame wrote:
>
> Hi Satya,
>
> On 26/07/2011 19:26, Satya Sahoo wrote:
>> Hi Khalid,
>> >  No information about the process pe is inferred. The above merely 
>> specifies that there exists a process >execution, (which we don't 
>> know), such that isGeneratedBy(e1,pe,r1) and use(pe,e0,r0)
>> If we do not know about pe, then what new knowledge is being added to 
>> the provenance store using the above rule?
>>
>
> I don't think that such a rule was suggested to infer new information. 
> It was merely used to clarify what the time t refers to in the 
> assertion isDerivedFrom(b1,b2,t), i.e., whether t refers to the time 
> in which the process execution that generates b2 use b1, or the time 
> at which the process in question generates b2.
>
> Thanks, khalid
>
>> The information that a pe may exist anyway follows from our 'open 
>> world assumption'.
>>
>> > IMO, we cannot make this inference. The process execution pe may 
>> well generate e1 without using e0, even if >e0 is an input of that 
>> process execution.
>> I agree with your point - there may be an indirect dependency between 
>> e1 and e0 (if pe cannot be executed without e0 being present). But, 
>> defining the indirect dependency as the isGeneratedBy property may be 
>> inaccurate.
>>
>> Thanks.
>>
>> Best,
>> Satya
>>
>>
>> On Tue, Jul 26, 2011 at 4:26 AM, Khalid Belhajjame 
>> <Khalid.Belhajjame@cs.man.ac.uk 
>> <mailto:Khalid.Belhajjame@cs.man.ac.uk>> wrote:
>>
>>
>>     Hi Satya,
>>
>>     On 26/07/2011 02:33, Satya Sahoo wrote:
>>>     Hi Luc,
>>>     >  I think there is a missing "inference" in the specification.
>>>     >If there isDerivedFrom(e1,e0) holds, then there exists a
>>>     process execution pe, and roles r0,r1, such that:
>>>     >isGeneratedBy(e1,pe,r1) and use(pe,e0,r0)
>>>
>>>     I am not sure how can we infer additional information (pe, r0,
>>>     r1) from limited information (e1, e0)? Did you mean, we have the
>>>     information about pe, r0, r1, and the link between them and (e1,
>>>     e0) already stored somewhere?
>>
>>     No information about the process pe is inferred. The above merely
>>     specifies that there exists a process execution, (which we don't
>>     know), such that isGeneratedBy(e1,pe,r1) and use(pe,e0,r0)
>>
>>
>>>
>>>     As an alternate, I think we can define the inference rule in the
>>>     opposite direction:
>>>     if there exists: isGeneratedBy(e1,pe,r1) and use(pe,e0,r0)
>>>     then: isDerivedFrom(e1,e0) holds true?
>>
>>     IMO, we cannot make this inference. The process execution pe may
>>     well generate e1 without using e0, even if e0 is an input of that
>>     process execution.
>>
>>     Thanks, khalid
>>
>>
>>>
>>>     Also, if we consider the above alternate version of the rule, we
>>>     need to define whether isDerivedFrom "existentially dependent"
>>>     on "isGeneratedBy" and "use" properties, in other words only
>>>     if isGeneratedBy(e1,pe,r1) AND use(pe,e0,r0) already exist can
>>>     we have isDerivedFrom(e1,e0)? Or, isDerivedFrom can be
>>>     independently asserted?
>>>
>>>     Best,
>>>     Satya
>>>
>>>     On Mon, Jul 25, 2011 at 4:21 AM, Luc Moreau
>>>     <L.Moreau@ecs.soton.ac.uk <mailto:L.Moreau@ecs.soton.ac.uk>> wrote:
>>>
>>>
>>>
>>>         I'd like to refer to the missing inference I mentioned in a
>>>         separate thread:
>>>
>>>         I think there is a missing "inference" in the specification.
>>>
>>>         If there isDerivedFrom(e1,e0) holds, then there exists a
>>>         process execution pe, and roles r0,r1,
>>>         such that:
>>>          isGeneratedBy(e1,pe,r1) and use(pe,e0,r0)
>>>
>>>
>>>         So, given isDerivedFrom(e1,e0), I would argue that there are
>>>         potentially four
>>>         notions of time associated with this derivation:
>>>         - beginning of pe
>>>         - end of pe
>>>         - use of e0
>>>         - generation of e1
>>>
>>>         Paul, in your proposal, were you referring to any of these 4
>>>         instants, or
>>>         did you have another notion of time not captured yet?
>>>
>>>
>>>         Luc
>>>
>>>
>>>
>>>         On 07/24/2011 09:12 PM, Paul Groth wrote:
>>>
>>>             Something like that...I need to look at the exact
>>>             definition of derived from.
>>>
>>>             Paul
>>>
>>>             On Jul 24, 2011, at 20:43, Khalid
>>>             Belhajjame<Khalid.Belhajjame@cs.man.ac.uk
>>>             <mailto:Khalid.Belhajjame@cs.man.ac.uk>>  wrote:
>>>
>>>
>>>
>>>                 Ok, I must admit I didn't understand that. Just to
>>>                 clarify, when one say
>>>                 isDerivedFrom(b1,b2,t), does that means that b2 was
>>>                 created at t?
>>>
>>>                 Thanks, khalid
>>>
>>>
>>>                 On 24/07/2011 18:33, Paul Groth wrote:
>>>
>>>                     Hi Khalid,
>>>
>>>                     I don't think this is what I mean.
>>>
>>>                     It's not when the assertion was made. It's when
>>>                     the derivation occurred according to the asserter.
>>>
>>>                     Just as with use and generation. It's the time
>>>                     at which these events occur according to the
>>>                     asserter.
>>>
>>>                     Thanks
>>>                     Paul
>>>
>>>                     On Jul 24, 2011, at 18:08, Khalid
>>>                     Belhajjame<Khalid.Belhajjame@cs.man.ac.uk
>>>                     <mailto:Khalid.Belhajjame@cs.man.ac.uk>>   wrote:
>>>
>>>
>>>                         On 24/07/2011 15:35, Myers, Jim wrote:
>>>
>>>                             (The time is not the interval over which
>>>                             the derivation relation is
>>>                             valid - in the same way the time on USED
>>>                             is not the time when that
>>>                             relation is valid (it would be if the
>>>                             semantics were 'in use during
>>>                             interval t') - both just describe the
>>>                             time when an enduring relationship
>>>                             was first formed.)
>>>
>>>                         Agreed, that what I was hinting to in my
>>>                         last response email to Paul.
>>>                         The time I was referring to in my email was
>>>                         the validity, but Paul, I
>>>                         think, was talking about the time where the
>>>                         derivation was formed.
>>>
>>>                         Which leads me to a new proposal. Instead of
>>>                         having the time as argument
>>>                         to USE, GENERATION and derivation, e.g.,
>>>                         isDerivedFrom(b1,b2,t). Would
>>>                         it be sensible to assume, instead, that
>>>                         every assertion may be
>>>                         associated with a time in which it was formed?
>>>
>>>                         Thanks, Khalid
>>>
>>>
>>>                              Jim
>>>
>>>
>>>                                 -----Original Message-----
>>>                                 From: public-prov-wg-request@w3.org
>>>                                 <mailto:public-prov-wg-request@w3.org>
>>>                                 [mailto:public-prov-wg-
>>>                                 <mailto:public-prov-wg->
>>>                                 request@w3.org
>>>                                 <mailto:request@w3.org>] On Behalf
>>>                                 Of Khalid Belhajjame
>>>                                 Sent: Sunday, July 24, 2011 8:27 AM
>>>                                 To: Paul Groth
>>>                                 Cc: Provenance Working Group WG;
>>>                                 Provenance Working Group Issue
>>>
>>>                             Tracker
>>>
>>>                                 Subject: Re: PROV-ISSUE-43
>>>                                 (derivation-time): Deriviation
>>>                                 should have
>>>                                 associated time [Conceptual Model]
>>>
>>>
>>>                                 Hi Paul,
>>>
>>>                                 On 24/07/2011 13:13, Paul Groth wrote:
>>>
>>>                                     Hi Khalid
>>>                                     But why can't I say that a
>>>                                     newspaper article is derived from a
>>>
>>>                             picture at a
>>>
>>>                                 particular time? Or for that matter
>>>                                 over a period of time.
>>>
>>>                                 The way I see it, is that there will
>>>                                 be a bob representing the
>>>
>>>                             newspaper article
>>>
>>>                                 and another representing the
>>>                                 picture. If there is evidence that the
>>>
>>>                             latter is
>>>
>>>                                 derived from the former, then the
>>>                                 derivation will always hold between
>>>
>>>                             those
>>>
>>>                                 two bobs.
>>>
>>>                                 Now, that I am writing this email, I
>>>                                 am wondering whether we are
>>>
>>>                             referring to
>>>
>>>                                 the same notion of time. In your
>>>                                 statement, isDerivedFrom(b1,b2,t), I
>>>
>>>                             think you
>>>
>>>                                 mean t is used to refers to the time
>>>                                 in which the derivation assertion
>>>
>>>                             was
>>>
>>>                                 made, whereas what I was thinking of
>>>                                 is the (period of) time in which
>>>
>>>                             the
>>>
>>>                                 derivation holds. Is that the case?
>>>
>>>                                 Thanks, khalid
>>>
>>>                                     The time is when the derivation
>>>                                     occurred not when it applies.
>>>
>>>                                     Thanks
>>>                                     Paul
>>>
>>>                                     On Jul 24, 2011, at 13:06, Khalid
>>>
>>>                                 Belhajjame<Khalid.Belhajjame@cs.man.ac.uk
>>>                                 <mailto:Khalid.Belhajjame@cs.man.ac.uk>>
>>>                                     wrote:
>>>
>>>                                         Hi Paul,
>>>
>>>                                         I think that "Use" and
>>>                                         "Generation" should be
>>>                                         associated with time.
>>>                                         However, I don't think we
>>>                                         should associate time to
>>>                                         derivation.
>>>                                         I would argue that
>>>                                         isDerivedFrom(b1,b2) holds
>>>                                         all time. Although b1
>>>                                         and
>>>                                         b2 may no longer exist,
>>>                                         isDerivedFrom(b1,b2) is
>>>                                         still valid.
>>>
>>>                                         Thanks, khalid
>>>
>>>
>>>                                         On 23/07/2011 16:46,
>>>                                         Provenance Working Group
>>>                                         Issue Tracker wrote:
>>>
>>>                                             PROV-ISSUE-43
>>>                                             (derivation-time):
>>>                                             Deriviation should have
>>>
>>>                             associated
>>>
>>>                                             time [Conceptual Model]
>>>
>>>                                             http://www.w3.org/2011/prov/track/issues/43
>>>
>>>                                             Raised by: Paul Groth
>>>                                             On product: Conceptual Model
>>>
>>>                                             Other relationships have
>>>                                             time associated with
>>>                                             them (e.g. use,
>>>                                             generation, control)
>>>
>>>                                             There is no optional
>>>                                             time associated with
>>>                                             derivation.
>>>
>>>                                             Suggested resolution is
>>>                                             to add the following to
>>>                                             the definition of
>>>
>>>                                 isDerivedFrom:
>>>
>>>                                             -  May contain a
>>>                                             "derived from time" t,
>>>                                             the time or time intervals
>>>                                             when b1 was derived from b2
>>>
>>>                                             Example:
>>>                                             isDerivedFrom(b1,b2, t)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>         -- 
>>>         Professor Luc Moreau
>>>         Electronics and Computer Science   tel: +44 23 8059 4487
>>>         <tel:%2B44%2023%208059%204487>
>>>         University of Southampton          fax: +44 23 8059 2865
>>>         <tel:%2B44%2023%208059%202865>
>>>         Southampton SO17 1BJ               email:
>>>         l.moreau@ecs.soton.ac.uk <mailto:l.moreau@ecs.soton.ac.uk>
>>>         United Kingdom http://www.ecs.soton.ac.uk/~lavm
>>>         <http://www.ecs.soton.ac.uk/%7Elavm>
>>>
>>>
>>>
>>
>>
>

-- 
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, 27 July 2011 14:44:54 GMT

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