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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: Tue, 17 Jan 2012 11:30:09 +0000
Message-ID: <EMEW3|a750b5159ff64fc862221106f76f111do0GBUC08L.Moreau|ecs.soton.ac.uk|4F155BC1.3090002@ecs.soton.ac.uk>
To: public-prov-wg@w3.org
Here is a suggestion:

For every imprecise derivation, we can associate the time at which e2 is 
generated.

Hence,
   wasDerivedFrom(e2,e1,t,attrs)

is a shortcut for:

   wasDerivedFrom(e2,e1,attrs)
   wasGeneratedBy(e2,t)

Note that this assumes that activity is not mentioned in generation record.
This is outstanding ISSUE-205.

Cheers,
Luc


On 01/17/2012 11:24 AM, Luc Moreau wrote:
> Hi Paul,
>
> Still trying to tackle this outstanding issue.  what are your views on 
> this last message?
>
> Thanks,
> Luc
>
> On 11/30/2011 02:39 PM, Luc Moreau wrote:
>> Hi Paul,
>>
>> Trying to come back to this issue, now that we have revised the 
>> notion of derivation.
>>
>> While  I am sympathetic to the idea of "short-cuts" to facilitate 
>> life of asserters,
>> I am also keen to stick to some (unwritten) design principles.
>>
>> 1. There should be one and only one place where a given piece of 
>> information can
>>    be placed in the data model. Failing to do so, then, asserters 
>> won't know where to
>>    assert information. Furthermore, the data model will have to 
>> specify what it means
>>    when places for a given piece of information contain different 
>> values.
>>
>>    In this case, derivation time(=generation time) could be placed in 
>> a derivation and in
>>    a generation record.
>>
>> 2.  Uniformity. If we make this time optional in derivation, we 
>> should also make it on
>>     "specializations" of derivation such as wasSummaryOf etc.
>>     We don't do it.
>>
>> Ultimately, writing a derivation time (=generation time) requires 
>> precision.
>> We shouldn't do it with an imprecise record. In the new terminology, 
>> were you suggesting
>> to do have this option in imprecise-1 records? imprecise-n?
>>
>> Luc
>>
>> On 11/11/2011 04:26 PM, Luc Moreau wrote:
>>> Hi Paul,
>>> Remember that the activity may have been a long running service, 
>>> which started well before the entity was used,
>>> and vice-versa, it could have ended well after the other entity was 
>>> generated.
>>>
>>> Let us know what event you choose, and we'll encode this.
>>> Luc
>>>
>>> On 11/11/2011 15:52, Paul Groth wrote:
>>>> Hi Luc,
>>>>
>>>> Ok, I see what your asking. I think we can reuse the events. My 
>>>> general thought is that (at 10 am) applies to the activity (e.g. 
>>>> the anonymous activity that used the report). So that would map to 
>>>> either the start or end of the activity or both?
>>>>
>>>> I'm not sure what's nicest.
>>>>
>>>> Thanks,
>>>> Paul
>>>>
>>>> Luc Moreau wrote:
>>>>> Hi Paul,
>>>>>
>>>>> Comments interleaved.
>>>>>
>>>>> On 11/09/2011 08:53 AM, Paul Groth wrote:
>>>>>> Hi Luc,
>>>>>>
>>>>>> For me this is about, saying the following:
>>>>>>
>>>>>> blogpost wasDerivedFrom Report at 10am Thursday
>>>>>
>>>>> What do you mean by this: blogpost was generated at 10am?
>>>>>
>>>>>> Sure there is some process there, there may be an interval. But I 
>>>>>> just
>>>>>> don't want to assert all that information.
>>>>>
>>>>> I understand, but ultimately, I am trying to determine whether 
>>>>> there is
>>>>> a new special event 'derivation' to which
>>>>> time is associated with, or whether we can reuse generation/use 
>>>>> events
>>>>> or start/end events.
>>>>>
>>>>>> Again, my fundamental thing is that I want to assert derivation 
>>>>>> chains
>>>>>> without (knowingly) asserting anything about process.
>>>>>>
>>>>>> Maybe the point is I'm looking for a shortcut such that if I 
>>>>>> assert a
>>>>>> time it automagically infers that the e2, and e1 are on the same 
>>>>>> time
>>>>>> line using the same clock and are the same time?
>>>>>
>>>>> Inferring time line and same clock would be no good.
>>>>>
>>>>>> Does that make sense?
>>>>>>
>>>>>
>>>>> I still need you to clarify the intended semantics, specifically, 
>>>>> what
>>>>> notion of time you refer to.
>>>>> Then, when it's decided, we can express the short cut.
>>>>>
>>>>> My take on it, in the above example, you refer to the blogpost
>>>>> generation time.
>>>>>
>>>>>> Paul
>>>>>
>>>>> Luc
>>>>>> Luc Moreau wrote:
>>>>>>> Hi Paul,
>>>>>>>
>>>>>>> I'd like to come back to this issue, and see how we can solve it.
>>>>>>>
>>>>>>> The fully expanded notion of derivation, written
>>>>>>> wasDerivedFrom(e2,e1,pe,q2,q1),
>>>>>>> refers to the generation event for e2, and the use event for e1.
>>>>>>> So, they form an "interval".  If we have time information for
>>>>>>> each of these events (and assuming a same clock), we can compute 
>>>>>>> the
>>>>>>> duration
>>>>>>> of this interval.
>>>>>>>
>>>>>>> So, the question is, do you really have a use case, where you 
>>>>>>> don't want
>>>>>>> to assert the use/generation events (qualified usage/generation) 
>>>>>>> but
>>>>>>> want
>>>>>>> to express time?  Can you explain it?
>>>>>>>
>>>>>>> My concern is that we are at risk of introducing two 
>>>>>>> placeholders for
>>>>>>> the same time information
>>>>>>> (in derivation or use/generation events). Two placeholders for 
>>>>>>> time may
>>>>>>> result in inconsistent
>>>>>>> information.
>>>>>>>
>>>>>>> Luc
>>>>>>>
>>>>>>>
>>>>>>> On 07/23/2011 04:46 PM, 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
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 Tuesday, 17 January 2012 11:30:42 UTC

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