- From: Graham Klyne <graham.klyne@zoo.ox.ac.uk>
- Date: Sat, 01 Dec 2012 11:49:17 +0000
- To: Luc Moreau <l.moreau@ecs.soton.ac.uk>
- CC: W3C provenance WG <public-prov-wg@w3.org>
On 30/11/2012 17:30, Luc Moreau wrote: > Hi Graham, all, > > The staged document can be found at: > http://dvcs.w3.org/hg/prov/raw-file/default/links/releases/WD-prov-links-20121211/Overview.html > > > Let me know if you find any bug. > > I have added links to the dm/constraints sections that use the term 'aspect' and > I have also > added its informalmeaning. > > I didn't understand the conflict you suggested. Can you clarify? The conflict I see here is the implication that by simply making assertions about an entity you are somehow defining a new and changed entity. If I say that the provenance linking document is authored by you and Tim, am I thereby creating a new entity based on that document? I don't think so, but the text about defining a new entity for which the bundle is a new fixed aspect suggests that this is what is happening. > Finally, the notions of observer, perspective, context are a very significant > departure from what > we currently have, and the dm in general. I don't feel comfortable with them in > the document. To my mind, it's only by considering the context of an entity described by a bundle that the specialization-by-mention makes any sense at all. The elephant in the room here, which I think we have been dancing around, is that the mention construct introduces a context for the statements in a bundle. It's only through restricting the observations in a bundle to this (existential) context that I can make any sense of the idea that the bundle can be used to designate a specialization of an entity. Working from the implications of mention that Tim described to me at the F2F, I could only make sense of this by associating the bundle observations with a specialization, which led to the text that the group (reasonably) felt had no greater clarity. I think this will remain a muddled concept if it is not grounded in some notion of context or observation perspective. ... As a NOTE, I don't propose to make a big deal of this problem, but without greater clarity I fear that it will be of little practical value in creating a common view of what nature of specialization is introduced by a mention statement. Ultimately, what I think it needs is a formal semantics. #g -- > On 11/29/2012 06:15 PM, Graham Klyne wrote: >> http://dvcs.w3.org/hg/prov/raw-file/default/links/prov-links.html >> >> My comments are focused on Section 2, Conceptual Definition of Mention >> >> [[ >> An entity e1 may be mentioned in a bundle b, which contains some descriptions >> about this entity e1: how e1 was generated and used, which activities e1 is >> involved with, the agents e1 is attributed to, etc. Other bundles may contain >> other descriptions about the same entity e1. Some applications may want to >> augment the descriptions of entity e1 found in bundle b with other >> information. To this end, PROV allows a new entity e2 to be created and >> defined as a specialization of the preceding entity e1, and which presents at >> least an additional aspect: the bundle b containing some descriptions of e1. >> With this relation, applications that process e2 can know that the attributes >> of e2 may have been computed according to the descriptions of e1 in b. >> ]] >> >> "Some applications may want to augment the descriptions of entity e1 found in >> bundle b with other information" appears to be in conflict with the earlier >> statement "Other bundles may contain other descriptions about the *same* >> entity" (my emphasis). >> >> [[ >> The mention ◊ of an entity in a bundle (containing a description of this >> entity) is another entity that is a specialization of the former and that >> presents the bundle as a further additional aspect. >> >> An entity is interpreted with respect to a bundle's description in a domain >> specific manner. The mention of this entity with respect to this bundle offers >> the opportunity to specialize it according to some domain-specific >> interpretation. >> A mention of an entity in a bundle results in a specialization of this entity >> with extra fixed aspects, including the bundle that it is described in. >> ]] >> >> I have two concerns here: >> >> This definition leans heavily on the notion of "fixed aspects", but this term >> is not actually defined anywhere. >> >> Philosophically, I have difficulties with the implication that simply by being >> mentioned in a bundle somehow changes the entity itself. Suppose you are >> looking at an elephant, and writing down a description of that elephant. Then >> I come along and look at the elephant from a different perspective, and write >> down a description of what I see. We may put down different descriptions, but >> we are describing the *same* elephant. The fact of me doing that doesn't >> change the elephant in any way, nor does it affect the validity of your >> description concerning the elephant. Yet the idea that an observation is a >> new "fixed aspect" seems to suggest that this is act of observation makes it a >> different elephant. (Not allowing Heisenberg/observer effects here.) >> >> What I think is missing from your description is some notion of the >> perspective ("observation context") from which the descriptions in a bundle >> are derived. >> >> So here's my attempt to try and capture something of this: >> >> [[ >> Statements about an entity are based on information available from some >> perspective, and the extent of information available may be affected by the >> context of an observer that records it. The mention construct provides a way >> to make additional statements about the entity from the same context or >> perspective as other statements in a bundle. For example, one bundle may >> contain statements about a web page accessed from a network connection in USA >> which is presented containing comments authored by Americans, and another may >> contain statements about the same page accessed at the same time from China, >> which may contain a different set of comments. Deducible provenance about the >> contributors to this page may thus vary based on where it is accessed from. >> >> The mention construct provides a way to associate this additional contextual >> information with an entity, such as the location from which it has been >> accessed when making some provenance assertions. >> ]] >> >> #g >> -- >> >> >
Received on Saturday, 1 December 2012 11:53:32 UTC