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RE: PROV-ISSUE-7 (define-derivation): Definition for Concept 'Derivation' [Provenance Terminology]

From: Myers, Jim <MYERSJ4@rpi.edu>
Date: Fri, 3 Jun 2011 15:07:56 -0400
Message-ID: <B7376F3FB29F7E42A510EB5026D99EF2051E4A24@troy-be-ex2.win.rpi.edu>
To: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
CC: Graham Klyne <GK@ninebynine.org>, Luc Moreau <L.Moreau@ecs.soton.ac.uk>, <public-prov-wg@w3.org>
> > I think the answer should be obviously yes (I haven't thought of any
> > examples where I'd want 'no') - if some state of a thing (r2_s) is
> > used in a process instance to change another thing (r1) into some
> > state
> > (r1_s) then r1 is 'derived' from r2 *after the process instance
occurs*.
> Although that is one legitimate interpretation, I am not sure it is
the only
> way.
> There is more than one interpretation that one may think of:
> a resource r1 is derived from a resource r2 if:
> - a state of r1 is derived from a state of r2, or
> - the first state of r1, i.e., the one resulting from its creation, is
derived from a
> state of r2, or
> - the first state of r1, i.e., the one resulting from its creation, is
derived from
> the last state of r2, i.e., the state after which r2 does not change,
...

Fair enough. My personal opinion is that the first one is the best match
to realistic use cases and I'm also concerned that the others are too
'fragile' - if you look more closely, you can probably find that 'the
first state of r1' is really 'the first few states of r1', perhaps with
r2 involved with r1_s1.2, and I expect we don't want the derivation
relation to depend on how closely you look.

> > In reality, I think many of our examples have this sense (or could
> > have)
> > - we might create a file (r1) and then copy/paste gov. data in (new
> > state or r1) and claim r1 depends on the gov't data after that when
> > the file in its original state did not. Beyond the OPM -style set of
> > relations, I think the only addition needed to handle this is some
way
> > to connect a thing and an aspect of the thing capturing its state
> 
> Yes, I agree. One way of avoiding confusion is by specifying the state
(or what
> you call aspect) of the resource (thing) when talking about the
provenance.

I think we are all agreeing that this (drop to a more stateful level of
abstraction and use OPM-like relationships) is a better way to handle
things than a separate mechanism for mutable things). The part I'm
trying to emphasize is that I think there's a 'turtles-all-the-way-down'
issue in that I can keep thinking of more dimensions of state to
describe as I broaden the set of processes. Resource/state pretends
there are only two levels, FRBR defines 4 levels, and there are
orthogonal bits of state (e.g. we can have cracked/uncracked eggs,
warm/cold eggs, and warm-cracked eggs and all the other combinations) -
hence I'm pointing to a relationship - aspect of/more stateful
representation of/whatever term/set of terms we think we need - rather
than a label on a given thing as being a state or completely immutable.
If we're all agreeing that immutable means immutable from some
perspective ala Luc, and state means 'representation in which additional
aspects of state are tied to identity', then I'm game for using the
shorthand versions except when we see a paradox/issue arising from the
shorthand.

 -- Jim


> 
> Thanks, khalid
> 
> > (and I
> > would claim it might be that r2_s is not the complete state, just
more
> > than r2, so we should think about capturing the relationship 'more
> > stateful representation of' rather than trying to define two types
> > absolutely).
> >
> >   Jim
> >
> > -----Original Message-----
> > From: Khalid Belhajjame [mailto:Khalid.Belhajjame@cs.man.ac.uk]
> > Sent: Friday, June 03, 2011 8:15 AM
> > To: Myers, Jim
> > Cc: Graham Klyne; Luc Moreau; public-prov-wg@w3.org
> > Subject: Re: PROV-ISSUE-7 (define-derivation): Definition for
Concept
> > 'Derivation' [Provenance Terminology]
> >
> >
> > Hi Jim,
> >
> > On 03/06/2011 02:03, Myers, Jim wrote:
> >> What do you want to capture with derivation of mutable resources?
> > Simply that one mutable resource can be used in a process and
produce
> > another different mutable resouirce? If so, I'd ask why we should
> > consider this case any different than immutable?
> > To me there are issues that come out when considering the derivation
> > of mutable resources. To illustrate this, I will give a simple
example.
> > Consider a mutable resource r1, which was in a state r1_s1, and
> > consider a process execution that used as input a resource r2 in a
> > state  r2_s to transform the state r1_s1 to the state r1_s2.
> >
> > Given the above, we can say that r2_s contributed to the derivation
of
> > r1_s2.
> >
> > Now, answering the question "did the resource r2 contribute to the
> > derivation of the resource r1" is not obvious, or is it?
> >
> > PS: Sorry Luc, I know that we probably should stop talking about
this,
> > given that in yestreday's telecon we agreed that we will consider
> > "immutable things" or "things/values" that are immutable according
to
> > some viewpoint as you suggested.
> >
> > Thanks, khalid
> >
> >> (Does the fact that most of what we want to call immutable
resources
> >> are undergoing constant change (bits getting refresh charges, files
> >> moving about in memory caches, etc.) cause any issue with the basic
> >> OPM-style model? I think all of these cases are handled just fine
by
> >> OPM-style constructs and I'd argue further that the key concept
about
> >> artifacts was not complete immutability with respect to any process
> >> we can think of but immutability with respect to the processes
> >> involved in the provenance (Eggs used in cake baking do not come
out
> >> as modified eggs (they become a new cake), but an egg in the fridge
> >> and the warmer egg waiting to be mixed are considered the same egg
> >> only because we don't want to discuss/report on the warming process
> >> that occurred. The fact that an egg has mutability in its
temperature
> >> doesn't make it a bad artifact in OPM or cause trouble in reporting
a
> >> baking process...)
> >>
> >> The mutable case that presents a question is should we provide a
> > second mechanism to allow one to describe a process that changes the
> > state of a mutable resource?-to say that  egg with temperaturcold is
> > the same egg with temperature warm after a heating process. I
suspect
> > that we can't avoid this use case completely but we might not have
to
> > create a separate mechanism: If we allow a resource egg to be
> > associated with cold-egg and warm-egg resources, we can use the OPM
> > like mechanism
> > (cold-egg<-- heating<-- warm-egg) while adding cold-egg and warm-egg
> > are 'aspectsof" the same mutable egg which 'participates' in a
heating
> > process. I think this is general and minimally disruptive. One could
> > say that an egg participated in heating without creating other
> > resources, but one could not directly describe the temperature of
the
> > egg before and after heating without creating the cold and warm egg
> artifacts.
> >>    I think this also covers what we want from agents and sources -
we
> > want to convey that they participate in a process and, while their
> > state changes as they do so, we don't want to document their state
> changes.
> > But as Simon says we may still want to treat them (e.g. the Royal
> > Society) as resources and talk about their creation so it would be
> > valuable if they could just be artifacts in the context of
> > creation/founding type events. Today, we have agents and sources as
> > different types than artifact so there is no way to talk about their
> > founding, etc.
> >> --  Jim
> >>
> >>
> >>
> >> ________________________________
> >>
> >> From: public-prov-wg-request@w3.org on behalf of Graham Klyne
> >> Sent: Thu 6/2/2011 3:45 PM
> >> To: Khalid Belhajjame
> >> Cc: Luc Moreau; public-prov-wg@w3.org
> >> Subject: Re: PROV-ISSUE-7 (define-derivation): Definition for
Concept
> >> 'Derivation' [Provenance Terminology]
> >>
> >>
> >>
> >> Khalid Belhajjame wrote:
> >>> Hi Graham,
> >>>
> >>>    >I agree that many of the examples of derivation we have raised
> >>> relate to resource states.  But if, as has been suggested by
myself
> >>> and others, resource states are themselves resources>(especially
> >>> when named for the purposes of expressing a derivation), then such
> >>> derivations can equally be regarded as relating resources.  I
think
> >>> that's more a difference of terminology than>fundamental.
> >>>
> >>> Would it be fair then to say that in that view resources are
> >>> immutable resources?
> >> In the case of resources representing a snapshot of state, yes.
> >>
> >>> Which bring me to the question, do we want to express derivations
> >>> between mutable resources, or that is just something that we
should
> >>> avoid at this point?
> >> (I'm finishing this email after today's telecon, so it's a bit of a
> >> re-run.)
> >>
> >> I think that many of our use-cases are based on invariant values,
and
> >> the near-term goal is to find expression for these.  So we
definitely
> >> do want to express derivations between non-varying values.  But in
so
> >> doing, it's not clear to me (yet) that we need to exclude mutable
> >> resources, so I say let's keep our options open and not close off
any
> > possibilities that we don't have to.
> >> So my answer to avoiding mutable resources is: "yes and no".
> >>
> >> #g
> >> --
> >>
> >>
> >>> Thanks, khalid
> >>>
> >>>> Where I think I may diverge from what you say is that I would not
> >>>> limit such expressions of derivation to resources that happen to
be
> >>>> a state (or snapshot of state) of some resource.  I think
defining
> >>>> that distinction in a hard-and-fast way, that also aligns with
> >>>> various intuitions we may have about derivation, may prove
> >>>> difficult to achieve (e.g. as I think is suggested by Jim Meyers
in
> >>>>
http://lists.w3.org/Archives/Public/public-prov-wg/2011Jun/0015.htm
> >>>> l
> >>>> (*)).
> >>>>
> >>>> #g
> >>>> --
> >>>>
> >>>> (*) I just love the W3C mailing list archives - so easy to find
> >>>> links to messages, and thus capture provenance!
> >>>>
> >>>> Khalid Belhajjame wrote:
> >>>>> Hi,
> >>>>>
> >>>>>    From the discussion so far on derivation it seems that most
> >>>>> people tend to define derivation between resource states or
> >>>>> resources state representations, but not for resources.
> >>>>>
> >>>>> My take on this is that in a context where a resource is
mutable,
> >>>>> derivations will mainly be used to associate resource states and
> >>>>> resource states representations.
> >>>>>
> >>>>> That said, based on derivations connecting resource states and
> >>>>> resources state representations, one can infer new derivations
> >>>>> between resources. For example, consider the resource r_1 and
the
> >>>>> associated resource state r_1_s, and consider that r_1_s was
used
> >>>>> to construct a new resource state r_2_s, actually the first
state,
> >>>>> of the resource r2. We can state that r_2_s is derived from
r_1_s,
> >>>>> i.e., r_1_s ->   r_2_s. We can also state that the resource r_2
is
> >>>>> derived from the resource r_1, i.e., r_1 ->   r_2
> >>>>>
> >>>>> PS: I added a defintiion of derivation within this lines to the
> > wiki:
> >>>>> http://www.w3.org/2011/prov/wiki/ConceptDerivation
> >>>>>
> >>>>> Thanks, khalid
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> On 01/06/2011 07:49, Luc Moreau wrote:
> >>>>>> Hi Graham,
> >>>>>>
> >>>>>> Isn't it that you used the duri scheme to name the two resource
> >>>>>> states that exist in this scenario?
> >>>>>>
> >>>>>> In your view of the web, is there a notion of stateful
resource?
> >>>>>> Does it apply here?
> >>>>>>
> >>>>>> Thanks,
> >>>>>> Luc
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> On 31/05/11 23:57, Graham Klyne wrote:
> >>>>>>> Luc Moreau wrote:
> >>>>>>>> Graham,
> >>>>>>>>
> >>>>>>>> In my example, I really mean for the two versions of the
chart
> >>>>>>>> to be available at the same URI. (So, definitely, an uncool
> >>>>>>>> URI!)
> >>>>>>>>
> >>>>>>>> In that case, there is a *single* resource, but it is
stateful.
> >>>>>>>> Hence, there
> >>>>>>>> are two *resource states*, one generated using (stats2), and
> >>>>>>>> the other using (stats3).
> >>>>>>> Luc,
> >>>>>>>
> >>>>>>> I had interpreted your scenario as using a common URI as you
> > explain.
> >>>>>>> But there are still several resources here, but they are not
all
> >>>>>>> exposed on the web or assigned URIs.  I'm appealing here to
> >>>>>>> anything that *might* be identified as opposed to things that
> >>>>>>> actually are assigned URIs.   (For example, the proposed duri:
> >>>>>>> scheme might be used -
> >>>>>>> http://tools.ietf.org/id/draft-masinter-dated-uri-07.html)
> >>>>>>>
> >>>>>>> (And the URI is perfectly "cool" if it is specifically
intended
> >>>>>>> to denote a dynamic resource.  A URI used to access the
current
> >>>>>>> weather in London can be stable if properly managed.)
> >>>>>>>
> >>>>>>> (I think this is all entirely consistent with my earlier
stated
> >>>>>>> positions.)
> >>>>>>>
> >>>>>>> #g
> >>>>>>> --
> >>>>>>>
> >>>>>>>> Of course, if blogger had used cool uris, then, c2s2 and c2s3
> >>>>>>>> would be different resources.
> >>>>>>>>
> >>>>>>>> Luc
> >>>>>>>>
> >>>>>>>> On 05/31/2011 02:25 PM, Graham Klyne wrote:
> >>>>>>>>> I see (at least) two resources associated with (c2):  one
> >>>>>>>>> generated using (stats2), and other using (stats3).  We
might
> >>>>>>>>> call these (c2s2) and (c2s3).
> >>
> >>
> >>
> >>
> >
> >
> >
Received on Friday, 3 June 2011 19:09:36 GMT

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