- From: Luc Moreau <l.moreau@ecs.soton.ac.uk>
- Date: Wed, 26 Oct 2011 22:01:38 +0100
- To: Simon Miles <simon.miles@kcl.ac.uk>
- CC: Provenance Working Group WG <public-prov-wg@w3.org>
Hi Simon, Not sure which document it should go in, but it would definitely be worth writing this up! Luc On 26/10/2011 18:45, Simon Miles wrote: > Hi Luc, > > Wouldn't it be more appropriate in deliverable D6 (best practice > cookbook) to describe topics such as how to be robust to changes? It > could be in the primer, but we'd need to separate the gentle > introduction to how to use the model (which I would see as the > primer's main role) from the consideration of nuanced situations. > These could be distinct parts of the document. > > Thanks, > Simon > > On 26 October 2011 15:50, Luc Moreau<L.Moreau@ecs.soton.ac.uk> wrote: > >> Hi Simon and Paul, >> >> I see this simple example as good because it shows us that >> we don't have to write much to express provenance. >> Better some, than none! >> >> As always, this comes with some limitations, and I would >> see the role of the primer to discuss potential issues with these >> assertions as the world changes (e.g. video content changes). >> BTW, that's not typical of provenance, but it's typical of any metadata. >> >> The primer could discuss ways of making the assertions more >> robust to changes. A range of option exists, but they have to be discussed: >> - cool uris are really OK only for the publisher >> - adding the time at which >> <http://www.ted.com/talks/paul_bloom_the_origins_of_pleasure.html> >> was used would make those statements much stronger >> - adding further characterization, e.g. hash of the video, etc. >> >> Luc >> >> On 10/26/2011 10:53 AM, Simon Miles wrote: >> >>> Hi Paul, >>> >>> I think the argument you make is the same as implied by my example... >>> except that the conclusion is different. >>> >>> As you say, the provenance best practice could be to use permalinks. >>> So, in the example, the bloggers should use permalinks. They have no >>> control over what the original YouTube URL deferences to, so cannot >>> ensure it is a permalink. Unless they have special information, they >>> can only assume it is not, and so either they: >>> (a) cannot say anything about the video at all, or >>> (b) need to create their own permalink to refer to the video. >>> If doing (b), this new URI clearly should connect to the YouTube URL >>> as it is the video that the provenance is about. However, to make it >>> into a permalink, there must be something more which ensures it always >>> describes the same content, i.e. characterisation of the entity. The >>> provenance then looks like the PROV-OM examples rather than the simple >>> link. >>> >>> I'm not clear if you are arguing for option (a) in your email, i.e. >>> limit people to only refer to things in their provenance when they can >>> control those thing's immutability, but this seems very restrictive. >>> >>> I'm not saying I prefer the long-winded provenance data, just that it >>> appears the desire for interoperability makes it necessary beyond >>> limited cases. >>> >>> I think accounts and consistency are tangential issues - there is >>> nothing inconsistent in what is asserted, the inconsistency comes only >>> from the ambiguity of what is being asserted about. >>> >>> Thanks, >>> Simon >>> >>> >>> >>>> The point is that two different people are asserting it. We can't >>>> maintain consistency across the people. This is why we have accounts, no? >>>> >>>> I think one way to handle this is to have a best practice where we >>>> suggest people use permalinks (see >>>> http://en.wikipedia.org/wiki/Permalink) or cool-uris. Indeed, to me >>>> this is probably the best way to introduce entities. >>>> >>>> So overall, my suggestion would be to maintain simplicity but suggest >>>> people use uris that refer to content that doesn't change. >>>> >>>> But please bring this up in interoperability page. >>>> >>>> cheers, >>>> Paul >>>> >>>> >>>> >>>> Simon Miles wrote: >>>> >>>> >>>>> Paul, all, >>>>> >>>>> Just to properly understand why what is being discussed is important, >>>>> I wanted to expand your example to a larger use case. >>>>> >>>>> At time T, you say something about a video on your blog and assert: >>>>> <http://thinklinks.wordpress.com/2011/07/31/why-provenance-is-fundamental-for-people/> >>>>> prov:wasDerivedFrom >>>>> <http://www.ted.com/talks/paul_bloom_the_origins_of_pleasure.html>. >>>>> >>>>> At time T+1, the video is edited to introduce a previously missing >>>>> segment that undermines the message of your blog entry. The video URI >>>>> stays the same. >>>>> >>>>> At time T+2, I say something about the (updated) video on my blog and assert: >>>>> <http://inkings.org/2011/10/08/why-provenance-is-pointless/> >>>>> prov:wasDerivedFrom >>>>> <http://www.ted.com/talks/paul_bloom_the_origins_of_pleasure.html>. >>>>> >>>>> We could then observe: >>>>> - Even if the above use case doesn't happen to you, by using the >>>>> simplest form of provenance you are opening the possibility of it >>>>> happening and you would not even know about it. >>>>> - It doesn't help to say that the video owners shouldn't use the same >>>>> URL, because it is not under the control of either those creating or >>>>> consuming the provenance. >>>>> - There is nothing apparently wrong with either of our assertions >>>>> (except the lack of characterisation), and I don't know anything about >>>>> your blog so don't take it into account in my blog's provenance. >>>>> - It seems reasonable criteria for interoperability that if you read >>>>> Prov-DM from two separate sources referring to the same entity, then >>>>> either there is an error in (at least) one or they are mutually >>>>> consistent. I couldn't see what this would correspond to in the >>>>> interoperability discussion [1] though. >>>>> >>>>> Thanks, >>>>> Simon >>>>> >>>>> [1] http://www.w3.org/2011/prov/wiki/Interoperability >>>>> >>>>> >>>>> >>>> >>>> >>>> >>> >>> >>> >> -- >> 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 Wednesday, 26 October 2011 21:02:22 UTC