Re: prov-dm derivation: three proposals to vote on (deadline Wednesday midnight GMT)

Hi Simon,

I still need to think about your email, but let's assume for now that 
indeed we
need a non-transitive wasEventuallyDerivedFrom.  It would be good to 
hear from the WG
whether this is something that we want indeed.

Paul and I have received feedback that it is a terrible name, and to my 
mind, it was always a
placeholder to something more friendly.

So, can we come up with some naming that is intuitive?

Luc

On 10/11/2011 10:46, Simon Miles wrote:
> Hi Luc,
>
> My overall point is that derivation is both commonly not transitive,
> and you may not want or be able to assert anything about the
> underlying activities causing a derivation. If we want a transitive
> derivation-like relation (which I'm agnostic about, but accept the
> general desire), then it must have an explicitly weak semantics to
> allow it to be transitive.
>
>    
>> I didn't understand in your example of
>> the webpage why you decided to choose dependedOn or
>> wasEventuallyDerived.
>> It felt to me that you could have swapped them, and it would have still been
>> OK.
>>      
> In my example, the designer may assert that the first draft page was
> derived from the banner image ("DRAFT") that it contains, while the
> publisher may assert that the published page (excluding the banner)
> was derived from the first draft. But the published page is not
> derived from the banner image, because it would not make any
> difference should the banner have been different, or even not been
> present at all, e.g. the first draft could still have existed even if
> the banner had been deleted earlier. To allow a transitive
> derivation-like relation to exist, it must have semantics so weak as
> to allow the published page to be linked to the banner. I understood
> this weakened relation to be dependedOn. This relation does not remove
> the need for an actual derivation relation to be expressed. I don't
> have a strong opinion on whether a transitive relation needs to exist.
>
> The transitive-or-not distinction is also separate from whether
> derivation is tied to an activity or not. I might assert that a
> student's essay includes material from Wikipedia, without being
> involved in or observing the plagiarism itself. If the material had
> been copied from Wikipedia to a blog and the student copied from the
> blog, the derivation would still hold. I might be wrong in my
> assertion, but that is separate from the assertion's meaning. It seems
> that only allowing non-transitive derivation to be tied to an activity
> (i.e. having wasDerivedFrom and dependedOn without
> wasEventuallyDerivedFrom) requires us to constrain what the asserter
> knows in making an assertion, but surely the model should only say
> what the assertions mean?
>
>    
>> I would argue that there are two sketches, one conceptual leading
>> to the webpage, the other physical, created with the pen. And yes
>> one is complement of the other!
>>      
> I agree it could be asserted that way, but it would not be intuitive
> to me that these are separate entities, as it is the same thing at the
> same instant. I also can't see why the asserters of the two derivation
> relations would consider using different attributes to describe the
> sketch, unless they knew about the derivations each other was
> asserting and chose the attributes to avoid implying the invalid
> transitivity.
>
> Thanks,
> Simon
>
> On 9 November 2011 21:42, Luc Moreau<L.Moreau@ecs.soton.ac.uk>  wrote:
>    
>> Hi again,
>>
>> There was a consensus in the group that we wanted a transitive
>> derivation relation,
>> and that's why dependedOn was defined to be transitive.
>>
>> With the current prov-dm, we would be able to infer
>> dependedOn(webpage,pencil).
>>
>> You are arguing here, it's not the case. So, something is definitely broken.
>> So, this may question the existence of dependedOn.
>>
>> Of course, maybe your example is misleading.
>>
>>    wasEventuallyDerivedFrom(webpage, sketch1)
>>    wasEventuallyDerivedFrom(sketch, pencil)
>>
>> I would argue that there are two sketches, one conceptual leading
>> to the webpage, the other physical, created with the pen. And yes
>> one is complement of the other!
>>
>> So, this may not be a good counter for the non-transitivity of
>> wasEventuallyDerivedFrom.
>> Can you find another example where transitivity does not work for
>> wasEventuallyDerivedFrom?
>>
>> Further comment interleaved.
>>
>>
>> On 09/11/11 21:01, Simon Miles wrote:
>>      
>>> Hi Luc,
>>>
>>>
>>>        
>>>> I don't see why wasEventuallyDericedFrom can't be transitive?
>>>>
>>>>          
>>> Do you mean an instance or in general? If you mean in general, then
>>> for example, the webpage in the example was derived from the sketch,
>>> which was a pencil drawing on a sheet of paper. The sketch then was
>>> derived from the pencil. But the webpage was not derived from the
>>> pencil, as it would have been the same if the sketch was written in
>>> pen.
>>>
>>>
>>>        
>>>> It's also unclear how you decide between wasEventuallyDericed and dependendOn?
>>>>
>>>>          
>>> I'm not sure the kind of decision procedure you're looking for, but I
>>> might go for:
>>>
>>> A wasEventuallyDerivedFrom B if B being different would have meant A
>>> was different.
>>> If B was used in a process that generated an entity, C, and A
>>> wasEventuallyDerivedFrom C or A dependedOn C, then A dependedOn B.
>>>
>>>
>>>        
>> I don't see how what you suggest can work:
>>
>> used(p,B)
>> wasGeneratedBy(C,p)
>> wasEventuallyDerivedFrom(A,C)
>>
>> B could be used by p after C was generated.  How can you derive
>> a dependency between A and B?
>>
>> Let me repharse my question, I didn't understand in your example of
>> the webpage why you decided to choose dependedOn or wasEventuallyDerived.
>> It felt to me that you could have swapped them, and it would have still been
>> OK.
>>
>> Luc
>>
>>      
>>> Thanks,
>>> Simon
>>>
>>>
>>>        
>>>> Professor Luc Moreau
>>>> Electronics and Computer Science
>>>> University of Southampton
>>>> Southampton SO17 1BJ
>>>> United Kingdom
>>>>
>>>> On 9 Nov 2011, at 20:06, "Simon Miles"<simon.miles@kcl.ac.uk>    wrote:
>>>>
>>>>
>>>>          
>>>>> If you think that we need a non-transitive relation wasEventuallyDerivedFrom, can you explain why?
>>>>>
>>>>>            
>>>>
>>>>          
>>>
>>>
>>>        
>>
>>      
>
>
>

Received on Thursday, 10 November 2011 13:38:35 UTC