- 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>
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 UTC