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Re: PROV-ISSUE-8: defining generation in terms of `IVPT of'

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Fri, 10 Jun 2011 16:56:51 +0000
To: "Myers, Jim" <MYERSJ4@rpi.edu>
CC: "public-prov-wg@w3c.org" <public-prov-wg@w3c.org>
Message-ID: <EMEW3|603f506a2291bcf311273a048721c029n59HvH08L.Moreau|ecs.soton.ac.uk|B72C48F5-A214-4C80-ADF6-59F9C2634735@ecs.soton.ac.uk>
Jim and all,

Could you put forward a revised definition that addresses better your concerns?  

Professor Luc Moreau
Electronics and Computer Science
University of Southampton
Southampton SO17 1BJ
United Kingdom


On 10 Jun 2011, at 17:51, "Myers, Jim" <MYERSJ4@rpi.edu> wrote:

> 
>> 
>> Hi Jim
>> I think we are discussing two issues here.
>> 
>> 1. You suggest that the egg is itself an IVPT.
>> 
>>    There are different ways of looking at this:
>>    a. I was saying that an egg was a thing (identified, and  typed
> according to
>> an ontology)
>>        Then, it's a question of choice of a same ontology, or
> ontology
>> refinement, a classical problem,
>>        which we will not solve here.
> 
> I would claim the things in IVPT relationships with egg are also things
> that can be identified, typed, etc., not necessarily in the same class
> or ontology as 'egg'. (A logical picture is not the same class of thing
> as a jpg file corresponding to a particular manifestation of that
> image).
> 
>> 
>>    b. We could say that there is in an alternate account, which
> describes the
>> egg in terms of molecules.
> 
> Yes - my object in that account is 'set of molecules' and 'egg' is a
> convenient label for when those molecules are in a particular subset of
> all the configurations they can be in. If you say egg is an object and
> require a different type of thing to be used to describe things that
> invariant views of my set of molecules, I can't use it in my account,
> and we don't yet have any mechanism to make it clear that somehow my
> 'state of set of molecules' corresponds to your notion of 'egg'.
> 
>> 
>>    c.  Alternatively, we have IVPTs of IVPTs of IVPTs ...
>>         is there a base case? I fear we are going to reach quantum
> mechanics ...
> 
> I don't think we have to be afraid of this - and I would rephrase and
> say we have things of different types that can be in IVPT relationships
> with each other and your concern is then whether the fact that we can
> make deep hierarchies is an issue. I'd answer that by saying that the
> base case is in the middle - things like eggs are useful not because
> they are somehow true objects where other things are just views, they
> are useful views because of the natural/common processes they
> participate in. The fact that the model allows one to describe a set of
> quantum wave functions and claim one view of them is an egg doesn't mean
> that this will happen in practice (though there are scientists who do
> essentially this on a daily basis at the nano-scale). 
> 
> Whether it is truly 'turtles all the way down' is a philosophical
> question I'm not sure we have to answer - modeling it that way covers
> the middle ground without requiring any connection to real base objects
> (or more neutrally, without identifying a particular set of objects as
> real with all others some form of constructed view) - in this sense, I
> would ask you a) whether you see a consequence/limitation of a model
> that does not define which objects are 'real'? and b) given the debates
> about ontologies in the world, do you think we can reach a consensus on
> what the base reality is?
> 
> 
>> 
>> 2. You are commenting on the word modified.
>>      If I crack the egg,
>>        Y-> crack -> X
>>        Y and X are IVPTs of egg
>>        Y->X (we have a derivation)
>> 
>>      So looking at generation only, I feel it's OK to say the egg is
> modified, since
>> we
>>     have now a new IVPT Y about the same egg.
>> 
>> So, could you maybe make some suggestions on how you would revise the
>> definition?
> 
> I'm not sure what point you're making about the cracking example, but
> I'd say generation is just a case where we are more familiar/comfortable
> with the thing produced by a process execution as a useful thing to
> discuss/track the provenance of, and potentially where the inputs of the
> process execution are uninteresting. A chicken lays an egg not because
> we can't talk about a set of atoms that the chicken rearranges into a
> state we want to identify as an egg but because that view is not very
> useful, so identifying the 'set of atoms in the chicken' that is used to
> produce the egg or the 'set of atoms' that exists before and after egg
> laying that comprise the egg after laying isn't useful and we record
> chicken controls eggLaying which generates egg. Both/all variant
> accounts are valid and consistent in the model I'm advocating,
> specifically egg does not change type from being a real object to a
> state of a set of atoms - 'set of atoms' is a real thing that has a
> stateful view corresponding to a real thing called an egg (an IVPT
> relation with egg). The fact that 99+% of us would just report
> generation of an egg and stop is OK (good in fact - we don't want to
> needlessly talk about alternate views any more than we should feel
> pressure to expand all processes into fine grained steps or include info
> about the movement of electrons in describing computations).
> 
> Thanks,
> 
> Jim
>> 
>> Thanks,
>> Luc
>> 
>> 
>> On 06/10/2011 02:28 PM, Myers, Jim wrote:
>>> 
>>> 
>>>> -----Original Message-----
>>>> From: Luc Moreau [mailto:L.Moreau@ecs.soton.ac.uk]
>>>> Sent: Friday, June 10, 2011 3:26 AM
>>>> To: Myers, Jim
>>>> Cc: public-prov-wg@w3c.org
>>>> Subject: Re: PROV-ISSUE-8: defining generation in terms of `IVPT
> of'
>>>> 
>>>> Hi Jim,
>>>> 
>>>> I had not seen your comment in line, my responses are also inline.
>>>> 
>>>> On 10/06/11 02:28, Myers, Jim wrote:
>>>> 
>>>>> This would mean that a heating process modifies an egg to create a
>>>>> 
>>> warm egg,
>>> 
>>>> it does not transform a cold egg into a warm egg?
>>>> 
>>>>> Or do you mean both - a process execution can turn one thing into
>>>>> 
>>> another,
>>> 
>>>> these things can be considered IVPTs of a thing that participates
> in
>>>> 
>>> the process
>>> 
>>>> execution/ is modified by the process execution? And in an open
> world
>>>> assumption, a witness doesn't have to report the modified thing or
>>>> can
>>>> 
>>> decline
>>> 
>>>> to identify/report either of things in IVPT roles depending on
> their
>>>> 
>>> ability to
>>> 
>>>> observe and the use case they wish to enable?
>>>> 
>>>>> ________________________________
>>>>> 
>>>>> From: public-prov-wg-request@w3.org on behalf of Luc Moreau
>>>>> Sent: Thu 6/9/2011 6:44 PM
>>>>> To: Provenance Working Group WG
>>>>> Subject: PROV-ISSUE-8: defining generation in terms of `IVPT of'
>>>>> 
>>>>> 
>>>>> 
>>>>> Hi all,
>>>>> 
>>>>> - if a new thing is created, it is clear that we have a new IVPT
> of
>>>>> that thing
>>>>> 
>>>>> if a chicken creates an egg is it just an IVPT of an egg?
>>>>> 
>>>>> 
>>>> I would think the physical object is the egg.
>>>> I thought we had agreed that for a provenance purpose, we had to
> talk
>>>> 
>>> about
>>> 
>>>> an IVPT of that egg.
>>>> 
>>> But 'the egg' is also an IVPT of the stuff that goes into the cake -
> a
>>> temporary 'state' in which yolk and white are together and not
>>> mixed/chemically altered, etc.
>>> 
>>>> 
>>>>> - if the thing is modified, then it is a requirement that a new
> view
>>>>> 
>>> (IVPT) is
>>> 
>>>> generated ...
>>>> 
>>>>>         otherwise, it would still be a view that existed before
>>>>> 
>>>>> can't I say the egg was heated without reporting its cold and warm
>>>>> 
>>> states? I.e.
>>> 
>>>> don't we want to be able to report that something was modified
>>>> without
>>>> 
>>> having
>>> 
>>>> to report the IVPTs? A document was edited four times by different
>>>> 
>>> people but I
>>> 
>>>> don't wan't to/can't tell you what each wrote at each stage?
>>>> 
>>>>> 
>>>> These comments were made in the context of defining Generation of
> an
>>>> 
>>> IVPT.
>>> 
>>> OK - but you said "if the thing is modified"... For generation, I
>>> would say the chicken participates in an egg laying process
> execution
>>> that generates an 'egg'. That 'egg' is an IVPT of the chemicals in
> it
>>> (which existed before). The 'egg' can also have further/more
> stateful
>>> IVPTs that are more useful for discussing heating, cracking, etc.
> The
>>> sense in which generation is special is that it is a derivation from
>>> things we don't consider logically an aspect/IVPT of something
>>> greater. I.e. the 'mass of egg-bound chemicals' in the chicken just
>>> changes its state to become the 'egg', nothing really appears or
>>> disappears (conservation of mass and energy). Unless/until a
> scientist
>>> wants to look at the potential for different processing of chemicals
>>> going into the egg versus those used to build the chicken's own
> body,
>>> 'mass of egg-bound chemicals' isn't something we'd usually think
>>> about, but it's a valid perspective and consistent with the view of
> an
>>> egg being generated (both views can be drawn on the same graph in
> the
>> way I've been describing).
>>> 
>>> 
>>>> The document was edited four times could be expressed by 4 process
>>>> 
>>> execution
>>> 
>>>> and something like opm:wasTriggeredBy in between.
>>>> 
>>>> 
>>>>> - if the process execution was taking a long time to modify/create
>>>>> 
>>> the thing,
>>> 
>>>> there is only one
>>>> 
>>>>>     instant at which the (invariant!) IVPT appears
>>>>> 
>>>>> I thnk we could define it that way, but if a cracking process
> takes
>>>>> 
>>> time, saying
>>> 
>>>> the cracked egg appears instantaneously basically means you want
>>>> 
>>> 'cracked egg'
>>> 
>>>> to be defined by some threshold - the cracked egg might become more
>>>> 
>>> cracked
>>> 
>>>> over time ) invariant only in that it is always above the threshold
>>>> 
>>> and the
>>> 
>>>> instance of the creation of the IVPT relationship occurs ata
>>>> 
>>> aspecific instant.
>>> 
>>>>> 
>>>> Yes, agreed.
>>>> 
>>>> 
>>>>> - I think this captures well a stateful objects, where processes
> can
>>>>> 
>>> modify the
>>> 
>>>> object, resulting in
>>>> 
>>>>>     different IVPTs corresponding to the various states
>>>>> 
>>>>> IVPTs are not a separate kind of thing and their invariance is
>>>>> 
>>> relative. If they
>>> 
>>>> are truly immutable sates/snapshopts, they can only exist for an
>>>> 
>>> instant because
>>> 
>>>> some part of the state of the thing (a part we may not care about
>>>> such
>>>> 
>>> as age)
>>> 
>>>> will change immediately.
>>>> 
>>>>> 
>>>> I am not sure I agree, here. IVPTs are a view/perspective on a
> thing.
>>>> 
>>> Perhaps I should argue from the other direction - the notion of a
>>> thing is also a perspective/view. "eggs" don't exist - only
> temporary
>>> co-locations of particular molecules. Galton and Mizoguchi's paper
>>> argues that objects are defined by what processes you consider to be
>>> internal to and external to the object - if you change the set of
>>> processes you are concerned about, you describe the world using
>>> different objects. In this sense, eggs feel more 'real' because the
>>> set of processes we see happening frequently to them preserve
> aspects
>>> of their state, so egg as an IVPT is useful/predictive/etc.
>>> 
>>>> Alternative views asserted by other asserters may co-exit.
>>>> - it's a decaying egg
>>>> - it's a duck egg, not a hen egg
>>>> - it's a chocolate egg
>>>> 
>>>> 
>>> I agree, so again from the other direction - I don't see why 'egg'
> is
>>> more real/more correct/more special than any of these, they're all
>>> IVPTs.
>>> 
>>> 
>>>> It is a requirement of any specific perspective to be invariant.
>>>> 
>>> Invariant relative to a view in which only certain processes are of
>>> interest (are observable/reported?).
>>> 
>>> 
>>>> So, it's not a snapshot of the global egg state, but it's a
> snapshot
>>>> 
>>> according to a
>>> 
>>>> view.
>>>> 
>>>> An analogy would be several cameras pointing to a same egg.
>>>>  From one camera, the egg is still, no change occurring.
>>>>  From the other, we see a crack appearing.
>>>> So one asserter can describe change in a physical object, while
>>>> 
>>> another does not
>>> 
>>>> describe any change.
>>>> But it's the same egg.
>>>> 
>>> Right - those are two views of something. But that something is just
>>> another view - one camera sees a soup of chemicals that are swirling
>>> and mixing (slowly for an egg) while another sees one thing (the
> egg).
>>> Both of these are just IVPTs too. The chemical view is mutable by
> more
>>> processes than the egg view, but it is more persistent (it lasts
>>> longer because we've defined it in a way that the processes that can
>>> create/destroy it are less frequent).
>>> 
>>> I know that thinking of everything as an IVPT is not necessarily
>>> intuitive, and that one can argue that it is just one way to model
> the
>>> world/a philosophy, but I think it is a model that has the right
>>> conceptual power to deal with the use cases we have (and the general
>>> set we can envision) while also being one that, in practice, will
> fade
>>> away
>>> - most people will agree that 'egg' and not 'mass of chemicals' is a
>>> more useful IVPT to talk about and we'll see 'eggs' used in cake
>>> baking and the world will mostly look like OPM (straight
>>> thing-execution-thing chains), but we'll still have the power to
> drop
>>> down and talk about cracking or go up and talk about conservation of
> mass
>> when needed.
>>> 
>>> I also don't know what a coherent alternative is that, once we add
> in
>>> all the features necessary to cover the use cases, we'll like
> better.
>>> There are certainly other ways to model - my question really is
>>> whether there are others that will end up being more intuitive once
>>> all the needed features are dropped in.
>>> 
>>> -- Jim
>>> 
>>>  Jim
>>> 
>>>> Luc
>>>> 
>>>>> What do you think?
>>>>> 
>>>>> 
>>>>> 
>>>> 
>> http://www.w3.org/2011/prov/wiki/ConceptGeneration#Definition_of_Gene
>>>> r
>>>> 
>>>>> ation_by_Luc
>>>>> 
>>>>> Cheers,
>>>>> Luc
>>>>> 
>>>>> 
>>>>> 
>> 
>> --
>> 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 Friday, 10 June 2011 16:57:45 GMT

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