- From: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
- Date: Wed, 27 Jul 2011 19:55:25 +0100
- To: Satya Sahoo <satya.sahoo@case.edu>
- CC: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, public-prov-wg@w3.org
- Message-ID: <4E305F1D.3060301@cs.man.ac.uk>
Hi Satya, On 27/07/2011 18:24, Satya Sahoo wrote: > Hi Khalid, > >I don't think that such a rule was suggested to infer new > information. It was merely used to clarify what the time t >refers to > in the assertion isDerivedFrom(b1,b2,t), i.e., whether t refers to the > time in which the process execution >that generates b2 use b1, or the > time at which the process in question generates b2. > I am not sure we can infer anything about the time at which a process > uses b1 from isDerivedFrom(b1, b2, t) - one explanation of the > assertion isDerivedFrom(b1, b2, t) can be that b1 "starts existing" at > t and we know that b1 was derived from b2, hence we can say that b1 > was derived from b2 at t. Extending this interpretation, we may in > some cases, where we know about the process that generated b1, that > process generated b1 at t. > > The above explanation can be stated as the following rule: > if isDerivedFrom (b1, b2, t) and isGeneratedBy(b1, pe) then > isGeneratedBy(b1, pe, t). Agreed, assuming that t in isDerivedFrom (b1, b2, t) refers to the time at which b1 was created. Khalid > > Thanks. > > Best, > Satya > > On Wed, Jul 27, 2011 at 4:11 AM, Khalid Belhajjame > <Khalid.Belhajjame@cs.man.ac.uk > <mailto:Khalid.Belhajjame@cs.man.ac.uk>> wrote: > > > Hi Satya, > > > On 26/07/2011 19:26, Satya Sahoo wrote: >> Hi Khalid, >> > No information about the process pe is inferred. The above >> merely specifies that there exists a process >execution, (which >> we don't know), such that isGeneratedBy(e1,pe,r1) and use(pe,e0,r0) >> If we do not know about pe, then what new knowledge is being >> added to the provenance store using the above rule? >> > > I don't think that such a rule was suggested to infer new > information. It was merely used to clarify what the time t refers > to in the assertion isDerivedFrom(b1,b2,t), i.e., whether t refers > to the time in which the process execution that generates b2 use > b1, or the time at which the process in question generates b2. > > Thanks, khalid > > >> The information that a pe may exist anyway follows from our 'open >> world assumption'. >> >> > IMO, we cannot make this inference. The process execution pe >> may well generate e1 without using e0, even if >e0 is an input of >> that process execution. >> I agree with your point - there may be an indirect dependency >> between e1 and e0 (if pe cannot be executed without e0 being >> present). But, defining the indirect dependency as >> the isGeneratedBy property may be inaccurate. >> >> Thanks. >> >> Best, >> Satya >> >> >> On Tue, Jul 26, 2011 at 4:26 AM, Khalid Belhajjame >> <Khalid.Belhajjame@cs.man.ac.uk >> <mailto:Khalid.Belhajjame@cs.man.ac.uk>> wrote: >> >> >> Hi Satya, >> >> On 26/07/2011 02:33, Satya Sahoo wrote: >>> Hi Luc, >>> > I think there is a missing "inference" in the specification. >>> >If there isDerivedFrom(e1,e0) holds, then there exists a >>> process execution pe, and roles r0,r1, such that: >>> >isGeneratedBy(e1,pe,r1) and use(pe,e0,r0) >>> >>> I am not sure how can we infer additional information (pe, >>> r0, r1) from limited information (e1, e0)? Did you mean, we >>> have the information about pe, r0, r1, and the link between >>> them and (e1, e0) already stored somewhere? >> >> No information about the process pe is inferred. The above >> merely specifies that there exists a process execution, >> (which we don't know), such that isGeneratedBy(e1,pe,r1) and >> use(pe,e0,r0) >> >> >>> >>> As an alternate, I think we can define the inference rule in >>> the opposite direction: >>> if there exists: isGeneratedBy(e1,pe,r1) and use(pe,e0,r0) >>> then: isDerivedFrom(e1,e0) holds true? >> >> IMO, we cannot make this inference. The process execution pe >> may well generate e1 without using e0, even if e0 is an input >> of that process execution. >> >> Thanks, khalid >> >> >>> >>> Also, if we consider the above alternate version of the >>> rule, we need to define whether isDerivedFrom "existentially >>> dependent" on "isGeneratedBy" and "use" properties, in other >>> words only if isGeneratedBy(e1,pe,r1) AND use(pe,e0,r0) >>> already exist can we have isDerivedFrom(e1,e0)? Or, >>> isDerivedFrom can be independently asserted? >>> >>> Best, >>> Satya >>> >>> On Mon, Jul 25, 2011 at 4:21 AM, Luc Moreau >>> <L.Moreau@ecs.soton.ac.uk <mailto:L.Moreau@ecs.soton.ac.uk>> >>> wrote: >>> >>> >>> >>> I'd like to refer to the missing inference I mentioned >>> in a separate thread: >>> >>> I think there is a missing "inference" in the specification. >>> >>> If there isDerivedFrom(e1,e0) holds, then there exists a >>> process execution pe, and roles r0,r1, >>> such that: >>> isGeneratedBy(e1,pe,r1) and use(pe,e0,r0) >>> >>> >>> So, given isDerivedFrom(e1,e0), I would argue that there >>> are potentially four >>> notions of time associated with this derivation: >>> - beginning of pe >>> - end of pe >>> - use of e0 >>> - generation of e1 >>> >>> Paul, in your proposal, were you referring to any of >>> these 4 instants, or >>> did you have another notion of time not captured yet? >>> >>> >>> Luc >>> >>> >>> >>> On 07/24/2011 09:12 PM, Paul Groth wrote: >>> >>> Something like that...I need to look at the exact >>> definition of derived from. >>> >>> Paul >>> >>> On Jul 24, 2011, at 20:43, Khalid >>> Belhajjame<Khalid.Belhajjame@cs.man.ac.uk >>> <mailto:Khalid.Belhajjame@cs.man.ac.uk>> wrote: >>> >>> >>> >>> Ok, I must admit I didn't understand that. Just >>> to clarify, when one say >>> isDerivedFrom(b1,b2,t), does that means that b2 >>> was created at t? >>> >>> Thanks, khalid >>> >>> >>> On 24/07/2011 18:33, Paul Groth wrote: >>> >>> Hi Khalid, >>> >>> I don't think this is what I mean. >>> >>> It's not when the assertion was made. It's >>> when the derivation occurred according to >>> the asserter. >>> >>> Just as with use and generation. It's the >>> time at which these events occur according >>> to the asserter. >>> >>> Thanks >>> Paul >>> >>> On Jul 24, 2011, at 18:08, Khalid >>> Belhajjame<Khalid.Belhajjame@cs.man.ac.uk >>> <mailto:Khalid.Belhajjame@cs.man.ac.uk>> >>> wrote: >>> >>> >>> On 24/07/2011 15:35, Myers, Jim wrote: >>> >>> (The time is not the interval over >>> which the derivation relation is >>> valid - in the same way the time on >>> USED is not the time when that >>> relation is valid (it would be if >>> the semantics were 'in use during >>> interval t') - both just describe >>> the time when an enduring relationship >>> was first formed.) >>> >>> Agreed, that what I was hinting to in my >>> last response email to Paul. >>> The time I was referring to in my email >>> was the validity, but Paul, I >>> think, was talking about the time where >>> the derivation was formed. >>> >>> Which leads me to a new proposal. >>> Instead of having the time as argument >>> to USE, GENERATION and derivation, e.g., >>> isDerivedFrom(b1,b2,t). Would >>> it be sensible to assume, instead, that >>> every assertion may be >>> associated with a time in which it was >>> formed? >>> >>> Thanks, Khalid >>> >>> >>> Jim >>> >>> >>> -----Original Message----- >>> From: >>> public-prov-wg-request@w3.org >>> <mailto:public-prov-wg-request@w3.org> >>> [mailto:public-prov-wg- >>> <mailto:public-prov-wg-> >>> request@w3.org >>> <mailto:request@w3.org>] On >>> Behalf Of Khalid Belhajjame >>> Sent: Sunday, July 24, 2011 8:27 AM >>> To: Paul Groth >>> Cc: Provenance Working Group WG; >>> Provenance Working Group Issue >>> >>> Tracker >>> >>> Subject: Re: PROV-ISSUE-43 >>> (derivation-time): Deriviation >>> should have >>> associated time [Conceptual Model] >>> >>> >>> Hi Paul, >>> >>> On 24/07/2011 13:13, Paul Groth >>> wrote: >>> >>> Hi Khalid >>> But why can't I say that a >>> newspaper article is derived >>> from a >>> >>> picture at a >>> >>> particular time? Or for that >>> matter over a period of time. >>> >>> The way I see it, is that there >>> will be a bob representing the >>> >>> newspaper article >>> >>> and another representing the >>> picture. If there is evidence >>> that the >>> >>> latter is >>> >>> derived from the former, then >>> the derivation will always hold >>> between >>> >>> those >>> >>> two bobs. >>> >>> Now, that I am writing this >>> email, I am wondering whether we are >>> >>> referring to >>> >>> the same notion of time. In your >>> statement, isDerivedFrom(b1,b2,t), I >>> >>> think you >>> >>> mean t is used to refers to the >>> time in which the derivation >>> assertion >>> >>> was >>> >>> made, whereas what I was >>> thinking of is the (period of) >>> time in which >>> >>> the >>> >>> derivation holds. Is that the case? >>> >>> Thanks, khalid >>> >>> The time is when the >>> derivation occurred not when >>> it applies. >>> >>> Thanks >>> Paul >>> >>> On Jul 24, 2011, at 13:06, >>> Khalid >>> >>> Belhajjame<Khalid.Belhajjame@cs.man.ac.uk >>> <mailto:Khalid.Belhajjame@cs.man.ac.uk>> >>> wrote: >>> >>> Hi Paul, >>> >>> I think that "Use" and >>> "Generation" should be >>> associated with time. >>> However, I don't think >>> we should associate time >>> to derivation. >>> I would argue that >>> isDerivedFrom(b1,b2) >>> holds all time. Although b1 >>> and >>> b2 may no longer exist, >>> isDerivedFrom(b1,b2) is >>> still valid. >>> >>> Thanks, khalid >>> >>> >>> On 23/07/2011 16:46, >>> Provenance Working Group >>> Issue Tracker wrote: >>> >>> PROV-ISSUE-43 >>> (derivation-time): >>> Deriviation should have >>> >>> associated >>> >>> time [Conceptual Model] >>> >>> http://www.w3.org/2011/prov/track/issues/43 >>> >>> Raised by: Paul Groth >>> On product: >>> Conceptual Model >>> >>> Other relationships >>> have time associated >>> with them (e.g. use, >>> generation, control) >>> >>> There is no optional >>> time associated with >>> derivation. >>> >>> Suggested resolution >>> is to add the >>> following to the >>> definition of >>> >>> isDerivedFrom: >>> >>> - May contain a >>> "derived from time" >>> t, the time or time >>> intervals >>> when b1 was derived >>> from b2 >>> >>> Example: >>> isDerivedFrom(b1,b2, t) >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> -- >>> 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 Kingdom http://www.ecs.soton.ac.uk/~lavm >>> <http://www.ecs.soton.ac.uk/%7Elavm> >>> >>> >>> >> >> > >
Received on Wednesday, 27 July 2011 18:56:03 UTC