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Re: Forwarding a comment from SemTech...

From: Eric Stephan <ericphb@gmail.com>
Date: Sun, 10 Jun 2012 06:56:20 -0700
Message-ID: <CAMFz4jiNiM=1k7w6zo4GCym_N+=XPeLj9EsU4punrqsaUbNbqA@mail.gmail.com>
To: reza.bfar@oracle.com
Cc: public-prov-wg@w3.org
The recent questions sound similar to the foaf:Agent / dct:Agent
question that came up several years ago.  Foaf retained foaf:Agent as
part of its core and acknowledged the dct:Agent as an equivalence


On Sat, Jun 9, 2012 at 11:33 PM, Reza B'Far (Oracle)
<reza.bfar@oracle.com> wrote:
> Ivan (et. al.)
> I tried to answer the gentleman who asked the question by saying that there
> was an effort going on in providing the mapping.  Nevertheless, I think the
> discussion is worthwhile as Ivan is suggesting.  Also, for Ivan's benefit,
> we should probably merge this discussion with thread between Kai and other
> folks (which I'm cutting-pasting below -- alas, there is no good way to
> merge threads that I know of).
> --------
> Kai,
> I have added Antoine's feedback as Issue 405.
> Best,
> Daniel
> 2012/6/8 Kai Eckert <kai@informatik.uni-mannheim.de>
>> Hi all,
>> here is feedback from Antoine Isaac regarding the Dublin Core mapping.
>> Unfortunately I was not able to work on the mapping this week, I will get
>> back to it next week.
>> Cheers,
>> Kai
>> -------- Original-Nachricht --------
>> Betreff: Fwd: Re: Dublin Core - PROV Mapping, Call for Feedback (until
>> June 5th)
>> Datum: Wed, 6 Jun 2012 11:56:12 +0200
>> Von: Antoine Isaac <aisaac@few.vu.nl>
>> An: Kai Eckert <kai@informatik.uni-mannheim.de>, "Panzer,Michael"
>> <panzerm@oclc.org>
>> Hi Kai, Michael,
>> Something that I've forgotten to state in my hurry. Or course the only
>> document I've really reviewed carefully is the Primer. Especially, I did not
>> check the complex mapping document. I think for the Direct Mapping and the
>> PROV specialization, this is less a problem---they're much shorter, and my
>> comments on the corresponding sections in the Primer would apply to the
>> content of these two documents, as well...
>> I sincerely hope these late comments won't be a problem for you,
>> Antoine
>> -------- Original Message --------
>> Subject: Re: Dublin Core - PROV Mapping, Call for Feedback (until June
>> 5th)
>> Date: Wed, 6 Jun 2012 11:50:47 +0200
>> From: Antoine Isaac <aisaac@FEW.VU.NL>
>> Reply-To: DCMI Architecture Forum <DC-ARCHITECTURE@JISCMAIL.AC.UK>
>> Hi Kai, Daniel, Michael and Simon,
>> Thanks a lot for the work on this. In fact I found it a great help for an
>> outsider (from the Dublin Core community) to have a first glance into the
>> work of the PROV working group.
>> I have some comments that I'm hastily putting together below. Please
>> apologize if it's unclear sometimes, and of course sorry for the late
>> feedback. You just gave one week... hopefully it's still June 5 somewhere on
>> Earth.
>> Best,
>> Antoine
>> ====== PROV reference
>> It seems that you are using really "fresh" documents from the PROV working
>> group. E.g. the property prov:generatedAtTime can be found in
>> http://dvcs.w3.org/hg/prov/raw-file/default/ontology/Overview.html
>> but not in the latest official working draft
>> http://www.w3.org/TR/prov-o/
>> Putting the reference to the latest draft in your docs could be handy!
>> ====== Dublin Core as a Simple Provenance Vocabulary
>> I'm uncomfortable with the strict categorization of elements into
>> "descriptive" and "provenance" metadata. Some elements are questionable to
>> belong to one or the other. You've addressed already many doubts, but maybe
>> you should acknowledge that you categorization is not "hard" or if it is,
>> give more rationale for the questionable elements...
>> My personal list:
>> - hasPart, isPartOf: Perhaps isPartOf has indeed often a provenance
>> flavor, especially when it's used from one element of a collection to that
>> collection. But I'd argue many of their uses can be descriptive, especially
>> hasPart. Unless you consider a mereological description of objects (typical
>> example of a car having wheels) to be always about provenance?
>> - conformsTo, rights and accessRights may reflect provenance info (though
>> it is "derived")
>> - accrual properties: I wonder whether all should be in (accrualPolicy
>> seems interesting for provenance) or out (accrualMethod could be
>> questioned). But a mixed position seems strange.
>> By the way method-wise, should there be strict correspondence between the
>> elements in the "provenance" category and the ones that are mapped to a PROV
>> element in the direct mapping?
>> What does it say on an a given element, if it's in the "provenance"
>> category but is not mapped to PROV?
>> Other comment:
>> [
>> It can be questioned if a resource changes by being published, however, we
>> consider the publication as an action that affects the state of the resource
>> and therefore it is relevant for the provenance.
>> ]
>> -> if provenance is about "where does an object come from", then this one
>> is a no-brainer!
>> ====== Basic considerations
>> [
>> if a specialization of a document is generated by one activity and a
>> specialization is used by a different activity later in time,
>> ]
>> -> What does "specialization" mean, in practice? I know that it is a
>> notion from PROV, but the word is highly ambiguous, a Primer would benefit
>> from some (short) explanation here.
>> By the way yourself are using "specialization" for something else (the
>> extension of PROV for handling DC "nuances").
>> ====== What is ex:doc1?
>> [
>> it is semantically incorrect to have several activities that all generate
>> the same entity at different points in time.
>> ]
>> -> Please cite the PROV context explicitly here!
>> Many people (I'd expect most) will gladly accept that several activities
>> contribute to the realization of one same resource. Even in a FRBR or
>> CIDOC-CRM context, which are already seen as (too) fine-grained models by
>> many.
>> By the way, I think later you try indeed to relate to simpler approaches,
>> so that must mean you thing it is *not* semantically incorrect ;-)
>> ====== Direct mappings
>> dct:date rdfs:subPropertyOf prov:generatedAtTime .
>> seems dubious. dct:valid is a sub-property of dct:date, which means that
>> it is also a sub-property of prov:generatedAtTime. You correctly represent
>> this in the mapping document, btw. But I'm quite sure this relation does not
>> hold in absolute.
>> dct:rightsHolder rdfs:subPropertyOf prov:wasAttributedTo .
>> This also seems strange at first sight. Looking at the definition for
>> dct:rightsHolder:
>> "A person or organization owning or managing rights over the resource."
>> This may include some institution who manages/stores a resource on behalf of
>> its creator, or anyone who "owns" the resource.
>> I think is compatible with PROV's super-vague meaning of attribution
>> ("Attribution is the ascribing of an entity to an agent.",
>> http://www.w3.org/TR/prov-dm/). But that's quite a stretch from what many
>> Dublin Core readers will understand for "attribution". Perhaps you could
>> give some explanation!
>> ======= PROV Specializations (and rationale for complex mappings)
>> The constructs introduced and their mapping to PROV seem ok.
>> But I think you could say one sentence about the rationale of these
>> specializations. I understand the need to "properly reflect the meaning of
>> the Dublin Core terms". Yet, do we need to go for a solution that result in
>> having the complexity of patterns of PROV next to the semantic distinctions
>> made in DC? We could as well just keep the granularity of DC, in terms of
>> patterns. I.e., using the simple mappings between DC properties and the
>> related "short-cut properties" in the PROV patterns (e.g.,
>> prov:wasAttributedTo).
>> This of course relates for the rationale for having complex mappings in
>> the first step. There are several options that PROV offers, in terms of
>> granularity. Especially, having more or less fine distinctions for linking
>> agents to entities. For a same "creation data" PROV can represent direct
>> links between persons and created resource (prov:wasAttributedTo), links
>> between persons and resources via Activity (prov:wasAssociatedWith) and
>> links between persons and Activity via Roles.
>> Having all of these levels of granularity at once is probably more harmful
>> than beneficial, given the complexity of the PROV pattern in general
>> (especially with "specializations"!). Or are the complex mappings just an
>> *option* you provide? If yes, a small paragraph elaborating on this would be
>> useful for your primer. In fact, it may be enough to gather some sentences
>> you already have scattered in different sections.
>> ======= Complex mappings, Stage 1
>> [
>> A lot of blank nodes are created, however, keep in mind that we envision a
>> second stage that relates them and provides stable URIs for the entities.
>> ]
>> -> Everyone won't be ready to create and maintain URIs for all the
>> entity/activity/role splitting in the PROV pattern, certainly. What is the
>> application scenario for this? I guess it would depend. So maybe at this
>> stage it's safer to say that some applications would create URIs, some would
>> keep to blank nodes. And of course many others won't use the more complex
>> mappings.
>> Other comments:
>> - I don't get why you opted for a simpler mapping pattern for
>> "Entity/Entity (How)". It's quite equivalent to the sub-property mappings
>> you have in the "Direct mappings" sections. According to the PROV model, for
>> a simple "version" link you can create one or several creation activities,
>> as well as half a dozen of "in" and "out" views/specializations of the
>> document, which play each a different role in these activities.
>> I understand you would want a simple mapping (so do I) but in this Primer
>> perhaps you should make a bit clearer reference on why you made that choice
>> here, as opposed to the more complex mappings that are listed before this
>> one.
>> - Is Prov:Entity provided with any specific semantics? If not, then
>> perhaps you can remove the explicit rdf:type that links to it. That would
>> make the example graphs simpler.
>> ====== Conflating PROV specializations
>> I understand that the stage 2 of the complex mapping will "merge" a lot of
>> the "ins" and "outs" nodes of individual activities. This should already a
>> progress compared to the extreme atomization that is currently carried out.
>> I'm looking forward to seeing the details!
>> However, it seems this will still result in one entity being specialized
>> into at least as many "versions" as there will be activities. I expect many
>> in our community will just hate having that. In fact that could be smartly
>> related to modeling distinctions such as the ones made in FRBR.
>> But then (or even without it) we run into the kind of problems denounced
>> here: http://blogs.ecs.soton.ac.uk/webteam/2010/09/02/the-modeler/ ;-)
>> In this respect, it would be a good idea to at least make these
>> specialization distinctions *optional*. Is it really not possible to have
>> several activities carried out on a single instance of entity, say, the
>> ex:doc1 in your example?
>> ======= [end]
>>> Hello everyone,
>>> in the Dublin Core Metada Provenance Task Group (with the help of Simon
>>> Miles), we have released an initial DC to PROV mapping draft.
>>> The work has been divided in several documents to improve readability:
>>> - The mapping primer [1] explains the process followed to do the mapping,
>>> the main rationale of our decisions and our next steps.
>>> - The Direct Mappings document [2] shows the direct mappings found
>>> between DC and PROV (e.g., subPropertyOf relations).
>>> - The PROV Specializations document [3] extends PROV-O with some basic
>>> roles and properties to be able to perform the complex mappings.
>>> - Finally, the Complex-Mappings document [4] infers PROV statements from
>>> DC statements that are not covered by the direct mappings.
>>> Please give us your feedback on our approach and the documents within one
>>> week (until Tuesday, June 5th).
>>> We sent this mail both to the relevant DCMI mailinglists and the PROV
>>> mailinglist in order to reach consensus.
>>> We are on a quite strict timetable now and aim at finishing the mapping
>>> (Stage 2, and the mapping back from PROV to DC) until end of June to reach
>>> the state of a public draft.
>>> Daniel will briefly present the current state in the PROV call tomorrow.
>>> If you have any questions or comments, please don't hesitate to contact us.
>>> Thanks,
>>> Kai, Daniel, Michael and Simon.
>>> [1] https://github.com/dcmi/DC-PROV-Mapping/wiki/Mapping-primer
>>> [2] https://github.com/dcmi/DC-PROV-Mapping/wiki/Direct-Mappings
>>> [3] https://github.com/dcmi/DC-PROV-Mapping/wiki/Prov-Specializations
>>> [4] https://github.com/dcmi/DC-PROV-Mapping/wiki/Complex-Mappings-S1
> On 6/9/12 11:32 PM, Ivan Herman wrote:
> There was a presentation on Prov at SemTech, as you all know, done by Reza.
> There was a brief discussion regarding the relationship of Prov to Dublin
> Core, essentially asking why Prov uses its own Agent or Person and not the
> Dublin Core one. We told the commenter that there is a document coming up
> that makes connections and equivalences between the two. However, the
> persons (I think both were from governmental organizations) were not
> absolutely happy. Essentially, they said having, say, an owl equivalence set
> up between dct:Agent and prov:Agent is all good and does things on a
> theoretical level, but when a government agency has to choose which terms
> they want to use, it is very disturbing to have two formally defined one,
> and RDF environments do not necessarily handle owl equivalences. Ie, they
> would prefer if prov would simply use, say, dct:Agent outright, rather than
> having its own term (I have not checked whether there are more such
> 'equivalences' set u!
>  p between
> DC and Prov, or whether all the others are subclasses/subproperties).
> The argument is compelling, we should probably consider this.
> Cheers
> Ivan
> ----
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Sunday, 10 June 2012 13:56:50 UTC

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