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

Hi Luc,

OK, fine with me. The only name I've come up with so far is wasBasedOn
(just because based can be a synonym for derived or depended).

Thanks,
Simon

On 10 November 2011 13:37, Luc Moreau <l.moreau@ecs.soton.ac.uk> wrote:
> 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?
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>
>



-- 
Dr Simon Miles
Lecturer, Department of Informatics
Kings College London, WC2R 2LS, UK
+44 (0)20 7848 1166

Received on Thursday, 10 November 2011 13:55:27 UTC