Karin, thank you for your insights and the references!
I agree that flexibility is desirable. Would this in your view also imply that the range declaration of dcterms:type as rdfs:Class should be dropped?
As far as the use of SKOS is concerned, the creation of a formal thesaurus sounds much more complicated than it is. Instead of publishing a list of literals, people should IMHO be stimulated wrapping the literals in concepts.
I believe that from a practical perspective this method is easier than publishing formally defined Vocabulary Encoding Schemes (VES), which the DC-standard seems to prescribe wherever literals are used as property values (independently of whether this is actually done at a significant scale). Using a VES, one can write things like dcterms:subject "Napoleon"^^ex:myVES. Using simple tooling one could instead put all the literals in an Excel-sheet and import them in a thesaurus, so that you could then write dcterms:subject ex:NapoleonConcept. Subsequently, others could relate their terminology to the one in the thesaurus, using standard relations, which is not possible with a VES.
Different communities could use different concept schemes (thesauri) in their APs to restrict the property values of the same properties. -j
-----Original Message-----
From: DCMI Architecture Forum [mailto:[log in to unmask]] On Behalf Of Karen Coyle
Sent: dinsdag 18 augustus 2015 19:49
To: [log in to unmask]
Subject: Re: dcterms:type and SKOS
Jan,
I believe I understand your use case, but it is only one possible use of Dublin Core terms, and I feel it is essential that DC terms be suitable for a wide variety of communities. What makes dcterms one of the most used vocabularies in the LOV dataset [1] is precisely its flexibility.
Limiting dcterms:subject to skos:Concepts would likely discourage communities whose tradition does not include the creation of formal thesauri.
It makes sense to have an agreement with your data sharing partners about the expected values for properties. This is the basis for the DCMI work on application profiles [2][3] which extend the basic vocabulary to meet specific needs. APs also relate to work in progress on RDF validation [4][5]. The "best of all possible worlds" would be a very general and flexible vocabulary that can be integrated into specific applications but that also allows interconnection between disparate communities. Machine-actionable application profiles could make that possible.
As for the list of terms in the DC type vocabulary[9] - I see it as being rather naive. Library of Congress not only has its own list of genres [6], it has a list of lists of genres [7]. The total number must be in the high three digits. I also find interesting the FaBio/CiTO list, that is primarily based on academic articles[8]. "Type" is definitely a concept within a context, so will be defined differently in different communities, as we see already.
kc
[1] http://lov.okfn.org
[2] http://dublincore.org/documents/singapore-framework/
[3] http://dublincore.org/documents/profile-guidelines/
[4] http://wiki.dublincore.org/index.php/RDF_Application_Profiles
[5] http://www.w3.org/2014/data-shapes/wiki/Main_Page
[6] http://id.loc.gov/vocabulary/genreFormSchemes/marcgt.html
[7] http://id.loc.gov/vocabulary/genreFormSchemes.html
[8] http://sempublishing.sourceforge.net/
[9] http://dublincore.org/documents/dcmi-type-vocabulary/
On 8/17/15 12:56 PM, Jan Voskuil wrote:
> Hi Dan, and Karen,
> I've been thinking about the valuable point you raise --- thanks for doing so.
>
> Before going on, let me first ask: would you agree on the basic premise on which I started this discussion, namely, that the range of dcterms:type should not be rdfs:Class?
>
> The next question is about declaring the range of dcterms:subject and dcterms:type to be skos:Concept. I see your point about usefulness. I think this has to do with two fundamentally different approaches to the notion of "aboutness": the systematic approach versus the encyclopedic approach.
>
> In the encyclopedic approach, an article is seen as a set of statements about some RWO or FWO. The set of articles is flat, without a structure (apart from alphabetic ordering by the name of the RWO). This idea is driving Wikipedia and DBPedia and is part of their success and effectivity.
>
> In the systematic approach, articles are thought of as being about "subject headings". The subject headings together form a rich associative structure, in which the subject headings are connected to each other, which yields groupings that make sense from some perspective or for some purpose. This implies a notion of metamodeling. SKOS intends to capture this notion in a manner as concise and simple as possible.
>
> Is the systematic approach useful? That is quite a question to pose. It is certainly easy to make fun of (sometimes overly ambitious) attempts made in the past. See Borges' famous and hilarious taxonomy of animals in terms of those that belong to the Emperor, those drawn with a very fine camel hair brush, and some other such categories (see [1]). Another fundamental critique of hierarchical schemes such as DDC and UDC is the " rhizome metaphor" (see [2] and [3]). A beautiful, thoroughly non-philosophical account of the development of ideas underlying the systematic approach is [4]. That said, I think it is fair to say that the systematic approach has its usefulness, warts and all. Probably especially so in specific, delimited domains.
>
> Concluding, the statement that something is about something can mean two fundamentally different things, depending on the spirit in which of the two approaches the statement is made.
>
> There are two options for dcterms:subject (and dcterms:type).
>
> A. We leave the choice open to the user by not specifying a range for dcterms:subject. The property can mean two different things depending on the context in which it is used: a simple case of polysemy or even homonymy (or punning if you like).
>
> B. We urge users to make the choice explicitly by declaring dcterms:subject to have skos:Concept as range. In that case, one would say that the Wikipedia article has foaf:focus Bill_Clinton (to which it does not bear the dcterms:subject relation), while the biography fits under a particular subject heading, so that it bears the dcterms:subject relation to that heading, which in turn bears the foaf:focus relation to Bill_Clinton.
>
> It seems to me that option B is to be preferred, independent of your commitments towards either one of the two approaches towards aboutness.
>
> The reason for this is data quality. In the old days, we were used to, say, put the customer's date of birth in the field called telephone number because that field was not used by applications anyway. And everybody was happy. Now we put our data models on the Web, hoping to achieve unprecedented levels of interoperability at almost no cost at all. We do this in the realization that we cannot expect every data source to always adhere to every minute detail of the model. This is what Antoine pointed out previously: the philosophy schema.org, which says: " In the spirit of "some data is better than none", we will accept this markup [which does not comply to expectations, JV] and do the best we can."
>
> This also means that refined data is better than some data. In other
> words, the more careful data sources are about which particular
> properties they use, the more value others can extract from them. (Of
> course, up to a point, where the distinctions become so subtle that
> they become difficult to understand.)
>
> Under option B, a data source that uses dcterms:subject to relate articles to RWOs (and maybe even foaf:focus to relate articles to subject headings) is not a problem. We can happily use the data source, and even manipulate it using a range of methods to make it as valuable as possible. At the same time, however, a "high quality" data source that does make the distinctions as intended yields the same value or more at lower cost. Under option A, there is no real sense in which this data source is different in quality.
>
> So, to drive home the point I am (albeit somewhat laboriously) trying to make: in view of the existence and broad use of foaf:focus, it makes sense to restrict dcterms:subject and make the two disjoint in range. As opposed to leave it completely open to use dcterms:subject either as a synonym of foaf:focus or as something else.
>
> I hope I am not ranting. Does this make any sense? -Jan
>
>
> [1]
> https://en.wikipedia.org/wiki/Celestial_Emporium_of_Benevolent_Knowled
> ge [2] https://en.wikipedia.org/wiki/Rhizome_(philosophy)
> [3] http://rhizomik.net/html/rhizome/
> [4] http://www.catalogingtheworld.com/
>
>
>
>
>
> -----Original Message-----
> From: DCMI Architecture Forum [mailto:[log in to unmask]]
> On Behalf Of Dan Matei
> Sent: maandag 17 augustus 2015 11:46
> To: [log in to unmask]
> Subject: Re: dcterms:type and SKOS
>
> -----Original Message-----
> From: Jan Voskuil <[log in to unmask]>
> Date: Mon, 17 Aug 2015 07:55:22 +0000
>
>>
>> To express the relation between a metamodelling concept
>> (":NapoleonConcept") and the RWO/FWO (":NapoleonBonaparte"),
>> foaf:focus fits the bill quite nicely. (((---On a side note: I think
>> that there should be an equivalent of this property within the
>> SKOS-namespace.---)))
>
>
> I have difficulties to understand the practical usefulness of the
> distinction "NapoleonConcept" vs. RWO/FWO "NapoleonBonaparte" :-(
>
> How "NapoleonConcept" fits in the definitions:
>
> S: (n) concept, conception, construct (an abstract or general idea
> inferred or derived from specific instances)
> http://wordnetweb.princeton.edu/perl/webwn?s=concept&sub=Search+WordNe
> t&o2=&o0=1&o8=1&o1=1&o7=&o5=&o9=&o6=&o3=&o4=&h=
>
> or
>
> A SKOS concept can be viewed as an idea or notion; a unit of thought. However, what constitutes a unit of thought is subjective, and this definition is meant to be suggestive, rather than restrictive.
> http://www.w3.org/TR/skos-reference/#concepts
>
> ?
>
> Of course my idea of "Monica Bellucci" differs (somehow) of the real Monica Bellucci :-) However...
>
> Yes, I can see the usefulness of the distinction between different catalographic identities (as subjects), such as:
>
> Mark Twain vs. Samuel Langhorne Clemens
>
> Charles Lutwidge Dodgson vs. Lewis Carroll
>
> Enea Silvio Piccolomini vs. Pius II
>
> or even:
>
> Bill Clinton (as himself)
> Bill Clinton (as governor of Arkansas) Bill Clinton (as president of
> USA)
>
> But to consider them concepts ? Useful ?
>
> Dan Matei
>
--
Karen Coyle
[log in to unmask] http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600
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