- From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
- Date: Fri, 10 Jun 2011 19:04:06 +0000
- To: "Myers, Jim" <MYERSJ4@rpi.edu>
- CC: "public-prov-wg@w3c.org" <public-prov-wg@w3c.org>
Thanks Jim, this makes the discussion constructive. In this definition, you say when X didn't exist(before P) but you don't say when it starts to exist. Is it intended? Also, did you really mean before P began? Can you explain why ? Can X change, i don't understand what happens then? Does the last condition necessarily apply? Are you also saying there needs to be another notion? Modification? Professor Luc Moreau Electronics and Computer Science University of Southampton Southampton SO17 1BJ United Kingdom On 10 Jun 2011, at 18:14, "Myers, Jim" <MYERSJ4@rpi.edu> wrote: > Posted on the wiki - basically the same definition as from Jun and > Daniel with more discussion of how the IVPT concept and the idea of > modifiable objects relate. > -- Jim > >> -----Original Message----- >> From: Luc Moreau [mailto:L.Moreau@ecs.soton.ac.uk] >> Sent: Friday, June 10, 2011 12:57 PM >> To: Myers, Jim >> Cc: public-prov-wg@w3c.org >> Subject: Re: PROV-ISSUE-8: defining generation in terms of `IVPT of' >> >> 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 19:05:02 UTC