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Re: [SKOS] on ISSUE-71 and ISSUE-74

From: Antoine Isaac <aisaac@few.vu.nl>
Date: Fri, 22 Feb 2008 10:54:47 +0100
Message-ID: <47BE9BE7.7070900@few.vu.nl>
To: Alistair Miles <alistair.miles@zoo.ox.ac.uk>
CC: public-swd-wg@w3.org, public-esw-thes@w3.org

Hi Alistair,

Thanks for this summary. I think it explains quite appropriately the 
different positions. I will however try to defned myself, maybe 
explaining my position in clearer way

To sum up, I think I started with the position Alasdair explained a 
while ago [1]

> In the first case (intra-vocabulary relationships), all the concepts 
> form part of a coherent whole and the relationships can be seen as a 
> statement of fact. The relationships form part of the vocabulary, 
> meaning that if you make use of the vocabulary then you accept all the 
> intra-vocabulary relationships.
>
> In the second case (inter-vocabulary mappings), the mappings between 
> the concepts are "fuzzier" and are more a statement of one person's, 
> or group's, beliefs. The vocabularies can be used without accepting 
> the statements made about the mappings.

But then I thought about KOS enrichment and KOS extension, which I 
believe call respectively for intra-scheme mapping links and 
inter-scheme "paradigmatic" ones, therefore blurring the lines
(but of course maybe we can find different solutions from the ones I've 
put in the Primer [4])

So for me the difference between mapping and "paradigmatic" relations 
would not be along the inter-scheme/intra-scheme dimensions but along:
- provenance & authority: "paradigmatic" links are endorsed by the 
authority that created the scheme
- inherence of the relation: "paradigmatic" links are inherently part of 
a concept's meaning, while mapping are mere accidents (different 
applications can map a concept to different concepts, depending on 
mapping technique and/or requirements)
Actually since the begining, I had understood "paradigmatic" as 
"defining the meaning of concepts"...

Now I would make a single, very important comment on your mail, which 
generally raise fair arguments except for the following one which is to 
me way to optimistic

> As a general design principle, I say that no property should
> ever be expected to carry greater authority or trust than another
> property, because such an expectation cannot be supported in practice.
> Authority and trust can only be conveyed, via provenance, outside the 
> graph.

Of course in theory they are good and bad ways to do model things. In an 
ideal world, your point would surely work.
But honnestly I think the scenarios that need distinction between 
mapping and "paradigmatic" links are too important to rely on the very 
feable solutions we are currently proposing for provenance of 
relationship statements [2,3]
The design of a pragmatic, application-guided model such as SKOS must 
not be afraid to make "economies of representation" when a feature 
becomes too important to be treated by too complex patterns.

Cheers,

Antoine

[1] http://lists.w3.org/Archives/Public/public-esw-thes/2007Dec/0063.html
[2] http://www.w3.org/2006/07/SWD/track/issues/36
[3] http://www.w3.org/2006/07/SWD/track/issues/47
[4] http://www.w3.org/TR/skos-primer/#secextension , 
http://www.w3.org/TR/skos-primer/#secmapping
>
> Dear all,
>
> I've been trying to collect my thoughts on issues 71 and 74. Here's 
> where I've got to so far.
>
> === Background ===
>
> Antoine's email of the 17 Feb [1] discusses both issue 71 and issue 
> 74, and proposes resolutions to both. This email contains an argument 
> for a fundamental distinction between "paradigmatic" versus "mapping" 
> relations based on notions of authority and semantic commitment, and 
> hence for parallel vocabularies.
>
> Antoine's first email of 19 Feb [2] makes a new proposal for 
> resolution of issue 71, based on the argument of 17 Feb.
>
> Antoine's second email of 19 Feb][3] makes a new proposal for 
> resolution of issue 74, again based on the argument of 17 Feb.
>
> [1] http://lists.w3.org/Archives/Public/public-swd-wg/2008Feb/0062.html
> [2] http://lists.w3.org/Archives/Public/public-swd-wg/2008Feb/0076.html
> [3] http://lists.w3.org/Archives/Public/public-swd-wg/2008Feb/0077.html
>
> === Preamble ===
>
> First, a point of pedantry. "Paradigmatic" is used in BS 8723-2 to 
> denote links that are inherent in the meaning of the linked concepts.
>
> The idea in SKOS was always that broader, narrower and related, 
> whether used within a concept scheme or between concept schemes, 
> denote links between concepts which are inherent in the meaning of the 
> linked concepts. Therefore, broader, narrower and related mapping 
> links are just as "paradigmatic" as broader, narrower or related links 
> within a concept scheme.
>
> Below, I use "intra-scheme links" to mean broader, narrower or related 
> links between concepts in the same scheme, and I use "inter-scheme 
> links" to mean broader, narrower or related links between concepts in 
> different schemes.
>
> === Discussion ===
>
> If we are going to have separate, parallel vocabularies in SKOS for 
> intra-scheme versus inter-scheme links, then I want to make sure we 
> have clear, sound and valid reason(s) for doing so. Note especially 
> that no analogous pattern is present in OWL, and therefore we need to 
> justify our different approach.
>
> Let me start by trying to restate Antoine's position on intra-scheme 
> links, as points A-E below:
>
> A. The activity of constructing a concept scheme is typically carried 
> out by a single authority. This activity results in, among other 
> things, a set of intra-scheme links between the concepts of the 
> scheme. The properties skos:broader, skos:narrower and skos:related 
> should be used by such an authority to represent these intra-scheme 
> links.
>
> B. Because the properties skos:broader, skos:narrower and skos:related 
> are used, for the most part, by an authority as described above, then 
> they can in general be relied upon to carry a certain degree of 
> authority, without needing to question the provenance of any graph in 
> which they are used.
>
> C. The activity of constructing a concept scheme generally follows a 
> well-defined methodology, and is carried out by a single authority in 
> support of a known application. Therefore, the intra-scheme links 
> between concepts can generally be relied upon to carry a certain 
> degree of semantic soundness or intellectual consistency.
>
> D. Because the properties skos:broader, skos:narrower and skos:related 
> are used, for the most part, to represent intra-scheme links that 
> result from such an activity, then they can in general be relied upon 
> to carry a certain degree of semantic soundness or intellectual 
> consistency, without needing to question the provenance of any graph 
> in which they are used.
>
> E. The properties skos:broader, skos:narrower and skos:related may be 
> used in other ways, however because they are mostly used as described 
> above, then they can be trusted to, in general, represent intra-scheme 
> links with a relatively high degree of authority and intellectual 
> soundness or consistency, without needing to question the provenance 
> of any graph in which they are used.
>
> Let me now try to restate Antoine's position on inter-scheme links, as 
> points F-H below:
>
> F. The activity of constructing a mapping between two concept schemes 
> is typically carried out by a single authority, which differs from the 
> authorities who were responsible for developing each individual 
> scheme. Such an activity results in a set of inter-scheme links 
> between the concepts of the two schemes. The properties 
> skos:broadMatch, skos:narrowMatch, skos:relatedMatch and 
> skos:exactMatch should be used to represent these inter-scheme links.
>
> G. Because the properties skos:broadMatch, skos:narrowMatch, 
> skos:relatedMatch and skos:exactMatch are used, for the most part, as 
> described above, they cannot in general be relied upon to carry the 
> authority of either party responsible for the construction of the 
> individual concept schemes.
>
> H. Although the activity of constructing a set of mapping links 
> between schemes might follow a well-defined methodology, the process 
> is fundamentally different from the process of constructing links 
> between concepts within a scheme, because the mapping authority has no 
> control over the scope or organisation of each of the mapped schemes, 
> and therefore has to cope with a wide variety of content and 
> structure. Therefore, links that result from such an activity are 
> generally more variable, less intellectually consistent or sound, than 
> are links which result from the construction of a concept scheme.
>
> I. Because the properties skos:broadMatch, skos:narrowMatch, 
> skos:relatedMatch are used, for the most part, to represent 
> inter-scheme links which result from such an activity, they generally 
> carry a lower degree of semantic soundness or intellectual consistency 
> than do skos:broader, skos:narrower and skos:related.
>
> J. The properties skos:broadMatch, skos:narrowMatch, skos:relatedMatch 
> may be used in other ways, however because they are mostly used as 
> described above, then they can be trusted to, in general, represent 
> inter-scheme links with a relatively low degree of authority and 
> intellectual soundness or consistency, without needing to question the 
> provenance of any graph in which they are used.
>
> === My Position ===
>
> Let us consider the ways in which links between concepts might differ.
>
> There are links which are "authoritative", and there are links which 
> are not. There are links which are well-engineered and intellectually 
> sound, and there are links which are not. There are links which span 
> concept schemes, and there are links which do not. These are three 
> orthogonal dimensions. There is also, of course, a fourth dimension of 
> basic paradigmatic meaning, i.e. whether the link is broader, narrower 
> or related, which is again orthogonal to the first three.
>
> Antoine's position, as stated above, is that skos:broader and 
> skos:broadMatch share the same paradigmatic meaning, however 
> skos:broader is typically (but not always) intra-scheme, more 
> authoritative and more intellectually consistent, whereas 
> skos:broadMatch is typically (but not always) inter-scheme, less 
> authoritative and less intellectually consistent.
>
> This is quite a load for each of these properties to carry. My concern 
> is that, in practice, neither of these properties (skos:broader, 
> skos:broadMatch) can be relied upon to carry anything other than their 
> basic, paradigmatic meaning, and that therefore, in practice, they are 
> at best redundant, and at worst misleading. To use an analogy, if SKOS 
> were a security-critical technology, then any application which relied 
> on a fundamental difference between skos:broader and skos:broadMatch 
> would have a serious vulnerability.
>
> Authority depends on provenance, as does trust in intellectual 
> soundness. As a general design principle, I say that no property 
> should ever be expected to carry greater authority or trust than 
> another property, because such an expectation cannot be supported in 
> practice. Authority and trust can only be conveyed, via provenance, 
> outside the graph.
>
> Kind regards,
>
> Alistair.
>
Received on Friday, 22 February 2008 09:54:56 UTC

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