- From: Luc Moreau <l.moreau@ecs.soton.ac.uk>
- Date: Tue, 23 Oct 2012 10:59:37 +0100
- To: Paul Groth <p.t.groth@vu.nl>
- CC: "public-prov-wg@w3.org" <public-prov-wg@w3.org>
- Message-ID: <EMEW3|5eefdea0ed3cff49fa3603b09318fa59o9MAxe08l.moreau|ecs.soton.ac.uk|50866A89>
Hi Paul, The FAQ maybe? Luc On 10/22/2012 07:26 PM, Paul Groth wrote: > Hi Luc, > > This is quite a nice clarification. I wonder if there's somewhere we > can use this without adding it to the document? I think the > definitions stand on their own as they now stand. > > > ==Off topic== > In general, there's a "philosophy" that's never been really stated > somewhere that drops out of these clarifications that I think the > working group shares but may not be articulated concisely in a single > document. I think (some) of the key points of the philosophy are: > > 1) Scruffy ---> Proper > 2) Identify the fixed bits your talking about > 3) There's multiple kinds of provenance descriptions, we provide a > substrate for all > 4) PROV is extensible (it's a substrate) > > Maybe this should go in the overview document? > > cheers > Paul > > > > > > On Mon, Oct 22, 2012 at 11:50 AM, Luc Moreau <l.moreau@ecs.soton.ac.uk > <mailto:l.moreau@ecs.soton.ac.uk>> wrote: > > Dear all, > > I have drafted a response to the following issue. See > http://www.w3.org/2011/prov/wiki/ResponsesToPublicComments#ISSUE-462_.28Definition_of_Entity.29 > > I will implement the changes once I have a confirmation > the group is happy with them, and they satisfactorily address the > issue. > > >> ISSUE-462 (Definition of Entity) >> >> * Original >> email:http://lists.w3.org/Archives/Public/public-prov-comments/2012Jul/0009.html >> >> * Tracker:http://www.w3.org/2011/prov/track/issues/462 >> * Group Response: >> o The term 'entity' is intentionally defined in a liberal >> manner to avoid restricting users expressivity. >> Obviously, it shouldn't be too liberal, otherwise it >> would be all encompassing, without clear semantics. >> o The term 'entity' (and associated notions such as >> 'alternate', 'specialization') have been the subject of >> intense debate by the Working Group, and the definition >> reflects the compromise reached by the Working Group. >> o The term 'aspect' is not used here with a technical >> meaning and should be understood with its dictionary >> meaning 'A particular part or feature of something'. >> o PROV-Constraints, in its rationale section, expands on >> the notion of entity. >> o While an object/thing may change over time, an entity >> fixes some aspects of that thing for a period of time (in >> between its generation and invalidation). As opposed to >> other models of provenance (such as OPM), an entity is >> not an absolute state snapshot. Instead, it is a kind of >> partial state, just fixing some aspects. The rationale >> for this design decision is that it is quite challenging >> to find absolute state snapshots that do not change: the >> location of a file on a cloud changes, the footer of this >> Web page changes (as more people access it), etc. Hence, >> by allowing/some/aspects (as opposed to all) to be fixed, >> the PROV concept of 'entity' is easy to use. >> o We distinguish an 'aspect' from an 'attribute'. An >> attribute-value pair represents additional information >> about an entity (or activity, agent, usage, etc). In the >> case of an entity, attribute-value pairs provide >> descriptions of fixed aspects. So, the term 'aspect' >> refers to properties of the thing, whereas the term >> 'attribute' refers to its description in PROV. >> o PROV does *NOT* assume that all fixed aspects are >> described by attribute-value pairs. So, there may be some >> fixed aspects that have not been described. Obviously, >> without description, it's difficult to query or search >> over them. >> o According to PROV Constraint key-object (constraint 23), >> an entity has a set of attributes given by taking the >> union of all the attributes found in all descriptions of >> that entity. In other words, PROV does not allow for >> different attribute-value pairs to hold in different >> intervals for a given entity. >> o The attribute-value pairs of an entity provide >> information for some of the fixed aspects of an entity. >> + /This point may not have been clear, and requires >> text modification/. (see below) >> o A specific attribute of an entity is its identity. It is >> also assumed that it holds for the duration of the entity >> lifetime. >> + /This point may not have been clear, and requires >> text modification/. (see below) >> >> * References: >> o PROV constraints >> rationale:http://www.w3.org/TR/2012/WD-prov-constraints-20120911/#entities--activities-and-agents >> >> o entity/specialization/alternate >> definitions:http://www.w3.org/2011/prov/wiki/SpecializationAlternateDefinitions >> >> o Resolution on >> entity/specialization/alternate:http://www.w3.org/2011/prov/meeting/2012-05-03#resolution_2 >> >> o Key Constraints >> definition:http://www.w3.org/TR/2012/WD-prov-constraints-20120911/#dfn-key-constraints >> >> o Key-Object constraint >> 23:http://www.w3.org/TR/2012/WD-prov-constraints-20120911/#key-object >> >> * Proposed Changes to the document: >> o http://www.w3.org/TR/prov-dm/#entity.attributes: instead >> of "representing additional information about this >> entity." write "representing additional information about >> the fixed aspects of this entity." >> o http://www.w3.org/TR/prov-dm/#term-identifier: add the >> following. >> + Entity, Activity, and Agent have a mandatory >> identifier. Two entities (resp. activities, agents) >> are equal if they have the same identifier. >> + Generation, Usage, Communication, Start, End, >> Invalidation, Derivation, Attribution, Association, >> Delegation, Influence have an optional identifier. >> Two generations (resp. usages, communications, etc.) >> are equal if they have the same identifier. >> > > > Luc > > > On 07/25/2012 08:16 AM, Provenance Working Group Issue Tracker wrote: >> PROV-ISSUE-462 (entity-definition-precision): Definition o entity may be too liberal [prov-dm] >> >> http://www.w3.org/2011/prov/track/issues/462 >> >> Raised by: Paul Groth >> On product: prov-dm >> >> This is the issue forhttp://lists.w3.org/Archives/Public/public-prov-comments/2012Jul/0009.html >> >> from Jacco van Ossenbruggen >> >> >> > > -- > Professor Luc Moreau > Electronics and Computer Science tel:+44 23 8059 4487 <tel:%2B44%2023%208059%204487> > University of Southampton fax:+44 23 8059 2865 <tel:%2B44%2023%208059%202865> > Southampton SO17 1BJ email:l.moreau@ecs.soton.ac.uk <mailto:l.moreau@ecs.soton.ac.uk> > United Kingdomhttp://www.ecs.soton.ac.uk/~lavm <http://www.ecs.soton.ac.uk/%7Elavm> > > > > > -- > -- > Dr. Paul Groth (p.t.groth@vu.nl <mailto:p.t.groth@vu.nl>) > http://www.few.vu.nl/~pgroth/ <http://www.few.vu.nl/%7Epgroth/> > Assistant Professor > - Knowledge Representation & Reasoning Group | > Artificial Intelligence Section | Department of Computer Science > - The Network Institute > VU University Amsterdam -- 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 Tuesday, 23 October 2012 10:00:23 UTC