Re: PROV-ISSUE-66 (is-execution-a-bob): Why is process execution not defined as a characterised entity? [Conceptual Model]

Hi Simon,

Responses interleaved.

On 08/01/2011 12:39 PM, Simon Miles wrote:
> Hi Luc,
>
> To clarify, I (and Satya, I believe) was not suggesting PE=BOB, just
> that PE is a subclass of BOB.
>
>    

OK, my mistake, you did say subclass.


I can see a case for having a superclass for all "nodes" in a provenance 
graph,
it doesn't mean this should be a BOB.



>> I see a process execution as a set of events using/generating BOBs,
>> and temporally delimited by a start and end event.  This set of event is
>> said  by an asserter to be an identifiable activity.
>> This activity has an "effect" on the world, by all the BOBs it generates.
>>      
> I can see no problem with all the above.
>
>    
>> Its major downside is
>> the unknown meaning of using/generating a process execution.  It seems
>> also to mix use/generation/start/end.
>>      
> I think it is just that "use" and "generation" make sense when we are
> thinking of a PE as a general BOB, while start/end make sense when we
> are looking at it specifically as a PE. Same as for agent, where
> "controlled" only makes sense when seeing it as an agent specifically.
>
> Interpreting generation at least, seems clear enough. "Generation
> represents the creation of a new characterized entity by an activity.
> This characterized entity did not exist before creation." If the "new
> charactized entity" happens to be a actviity, then it means one
> activity has created another activity. That suggests that the
> action/event of generation = the start of the created execution.
>
> Use may be harder, as I'm not sure what "consumption" of a process
> execution would denote from the definition "Use represents the
> consumption of a characterized entity by an activity." However, I'm
> not clear what the implications of "consuming" a document are either.
> I think this just requires clarifying what "consuming a BOB" is
> intending to mean (a separate issue).
>
>    
>> So can you identify an example that we can't model with  PE<>BOB
>> but can with PE=BOB?
>>      
> I give it a go below, but even if this doesn't convince you and my
> counter-proposal was rejected, I still think the issue needs
> addressing somehow.
>
> To extend the File Scenario, we want to express the provenance of the
> first "copy" process execution, pe2.
>    processExecution(pe2,copy,t+2)
>
> Why did it come about? This seems not the same as saying what data it
> used or who "controlled" it, it is because Charles typed some text
> into a console at pressed return, which we can express as:
>    processExecution(pe7,command-typed,t+1.8)
>
> By my proposal, this would automatically imply (as is already done for
> "agent(x)"):
>    bob(e7)
>
> Now we can express that pe2, as a BOB, owes its existence to pe7.
>    isGeneratedBy(pe7,pe2,out)
>
> Why would we want to consider expressing the above? Perhaps we want to
> assert that Charles was typing the  commands on a small mobile device,
> which is why the email address was mistyped and the document (e4)
> failed to reach its intended recipient.
>    

We still haven't defined process ordering, and I would argue that
what you want to capture is some form of process ordering.
Specifically there is a "signal" from pe7 to pe2.


We haven't had time to define this in spec. Sorry.

I agree with you that this use case needs addressing. But I am not
convinced that making PE is a subclass of BOB is the right way to
go about it.

Luc


> Thanks,
> Simon
>
> On 1 August 2011 11:50, Luc Moreau<L.Moreau@ecs.soton.ac.uk>  wrote:
>    
>> Hi Simon,
>>
>> While I mentioned, endurant/perdurant, I was using them for intuition,
>> and didn't mean to formally introduce them in the definition.
>> You may be right, a BOB with temperature changing constantly, may not fit
>> the endurant/perdurant distinction. But I am not expert in this ontology.
>>
>> But, I don't see why this makes a case for PE=BOB. What use case do you
>> try to resolve by merging the two concepts?  Its major downside is
>> the unknown meaning of using/generating a process execution.  It seems
>> also to
>> mix use/generation/start/end.
>>
>> I see a process execution as a set of events using/generating BOBs,
>> and temporally delimited by a start and end event.  This set of event is
>> said  by an asserter to be an identifiable activity.
>> This activity has an "effect" on the world, by all the BOBs it generates.
>>
>> So can you identify an example that we can't model with  PE<>BOB
>> but can with PE=BOB?
>>
>> Luc
>>
>> On 08/01/2011 11:09 AM, Simon Miles wrote:
>>      
>>> Hi Luc,
>>>
>>> OK, I believe I understand your intuition, but would argue:
>>>
>>> 1. A process execution currently fits the definition of a BOB, as it
>>> has assertable characteristics, is identifiable, and is an entity,
>>> i.e. bounded.
>>>
>>> 2. I was not clear we wanted to restrict BOBs to endurants. For
>>> example, at the F2F1, Tim raised the case of expressing that something
>>> changed temperature by 10 degrees (and why), without asserting what
>>> the start and end temperatures were. If I remember correctly, you and
>>> I argued that the temperature change could be seen as an (invariant)
>>> attribute of a BOB, because BOBs are not necessarily instantaneous.
>>> And if I understand endurants and perdurants correctly, I think the
>>> change is a perdurant because at any moment, the change itself is not
>>> apparent.
>>>
>>> Intuitively, it seems reasonable that a process execution is something
>>> you can ask the provenance of ("why did this execution occur as it
>>> did?"). This might or might not be fully answered by saying what the
>>> execution used, who it was controlled by, when it started, and what
>>> recipe it followed.
>>>
>>> I recognise that it makes things complicated, in that a process
>>> execution (as a BOB) could be "generated" or "used" by another
>>> execution, but perhaps this is what we mean by the "ordering of
>>> processes" concept anyway. The existing definition "Generation
>>> represents the creation of a new characterized entity by an activity.
>>> This characterized entity did not exist before creation." seems to fit
>>> the notion of one process starting another one quite nicely.
>>>
>>> To be more constructive, here's my counter-proposal.
>>>
>>> * We add "characterized entity" to the process execution definition,
>>> e.g. "A process execution represents an activity which performs a
>>> piece of work. An activity is a kind of identifiable characterized
>>> entity."
>>>
>>> No other change seems necessary, though some explanation of the
>>> consequences may be needed. We might then have also covered "ordering
>>> of processes", at least in a causal sense (temporal ordering is
>>> different).
>>>
>>> Thanks,
>>> Simon
>>>
>>> On 1 August 2011 09:14, Luc Moreau<L.Moreau@ecs.soton.ac.uk>    wrote:
>>>
>>>        
>>>> Hi Simon,
>>>>
>>>> To me, process executions are the "verbs", whereas BOBs are the "nouns",
>>>> and therefore
>>>> belong to different categories.
>>>>
>>>> Several people have also mentioned they relate to perdurant/endurant in
>>>> formal ontologies.
>>>>
>>>> Being identifiable is therefore not the key characteristic!
>>>>
>>>> Regards,
>>>> Luc
>>>>
>>>>
>>>> PS. In a separate thread, you mentioned that IVPof could be used for
>>>> process executions.
>>>>      This may make sense, but in that case we simply need to change the
>>>> signature of IVP of:
>>>>           BOB x BOB   U   PE x PE
>>>>
>>>>
>>>>
>>>> On 07/29/2011 05:22 PM, Provenance Working Group Issue Tracker wrote:
>>>>
>>>>          
>>>>> PROV-ISSUE-66 (is-execution-a-bob): Why is process execution not defined as a characterised entity? [Conceptual Model]
>>>>>
>>>>> http://www.w3.org/2011/prov/track/issues/66
>>>>>
>>>>> Raised by: Simon Miles
>>>>> On product: Conceptual Model
>>>>>
>>>>> This was mentioned by Satya in the call, but I can't see it having been raised as an issue yet.
>>>>>
>>>>> As process executions are identified and may have attributes, including start and end time, are they kinds of characterised entities, similarly to agent? If not, why not?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>            
>>>> --
>>>> 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
>>>>
>>>>
>>>>
>>>> ______________________________________________________________________
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>>>>
>>>>
>>>>          
>>>
>>>
>>>        
>> --
>> 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
>>
>>
>>
>> ______________________________________________________________________
>> This email has been scanned by the MessageLabs Email Security System.
>> For more information please visit http://www.messagelabs.com/email
>> ______________________________________________________________________
>>
>>      
>
>
>    

-- 
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 Monday, 1 August 2011 11:57:38 UTC