- From: Antoine Isaac <aisaac@few.vu.nl>
- Date: Fri, 17 Oct 2008 10:14:28 +0200
- To: SWD WG <public-swd-wg@w3.org>
Hi all, Here's a new draft response to Doug on [ISSUE-164], which takes into account our latest discussion with Alistair. I propose we approve to send it at the next teleconference. Antoine -------- Dear Doug, Thank you for your comment in [1], which is copied at the end of this mail. Your remark on the respective emphasis given to KOS extension and KOS mapping is plain right. I think the WG indeed foresees more use cases for mapping than for extension, as it appears in the SKOS Use Cases and Requirements document [2]. Accordingly, your suggestion to change the order of the respective sections in the Primer will be implemented. Further, we plan to add the two following scoping sentences to these sections. For KOS mapping: [ Mapping is expected to be crucial for applications that use several KOSs at a same time, where these KOSs have overlapping scopes and need to be semantically reconciled -- examples of such application can be found in the SKOS Use cases and Requirements document (http://www.w3.org/TR/skos-ucr/#R-ConceptualMappingLinks). A key feature of mapping is the possibility to state that two concepts from different schemes have comparable meanings, and to precise how these meanings compare, even though they come from different contexts and possibly adhere to different modelling principles. ] For KOS extension: [ Extension of a KOS can be especially useful when its designers (or third party KOS publishers) want to achieve a better coverage of a (sub-)domain, while adhering to the principles that guided the design of the existing KOS -- e.g., by re-using some of its concepts. Explicit KOS extension and re-use can also be used as a modularization mechanim, when a family of articulated KOSs (or parts of an overarching vocabulary) is designed to cover several (sub-)domains, and its designers want to allow specific applications to operate on given selections of concepts. ] Regarding your last comment on the potential problems raised by extension and inclusion of concepts in different schemes. There was some discussion between us about explicitly discouraging it. To leave the door open for innovative approaches and scenarios, we would like to keep to neither encouraging nor discouraging this practice. We really have almost no experience here, so we prefer to say nothing and let the community define best practice in response to implementation experience. In fact if you believe this practice is potentially harmful, we encourage you to publish a brief best practice note and inform the SKOS community via the mailing list. We'd also be more than happy to set up a "SKOS community best practices" wiki page to collect links to such statements! Finally, about your request for saying "something on how KOS developers might publish a vocabulary in SKOS, while asserting some practical form of ownership". I it is about the possibility to represent the provenance of statements that "compose" a KOS (e.g. the skos:inScheme statements), we unfortunately cannot propose an easy way for doing this for the moment. The resolution SKOS ISSUE-36 [3] gives hints about how this has been left to future implementations, e.g. using RDF named graphs. The Primer also touches the issue in section 3.1 (in "Note—owl:imports and re-using KOSs") [4]. We could however be more explicit, and propose to replace [ If an application is concerned with provenance information, additional steps may be required in order to maintain the provenance of the imported triples. Such functionality is however currently outside the scope of SKOS. ] by [ If an application is concerned with practical provenance or ownership information, additional steps may be required in order to maintain the provenance or assert the authority of imported triples, using for instance RDF named graphs. Such functionality is however currently outside the scope of SKOS. ] I hope these modifications seem appropriate to you. Please do not hesitate to send further comments to this mail, your experience is really precious! Best regards, Antoine [1] http://lists.w3.org/Archives/Public/public-swd-wg/2008Oct/0062.html [2] http://www.w3.org/TR/skos-ucr/#Accepted [3] http://www.w3.org/2006/07/SWD/track/issues/36 [4] http://www.w3.org/TR/skos-primer/#secscheme > ISSUE-164: Extension vs mapping (SKOS Primer) > > http://www.w3.org/2006/07/SWD/track/issues/164 > > Raised by: Antoine Isaac > On product: SKOS > > Raised by Doug Tudhope in [1] > > Open world discussion and extension vs mapping in 3.1 and 3.2 > > I’m a little concerned about the relative emphasis apparently given to extension > vs mapping. The primer might be read as suggesting that the default way of > connecting two KOS is via extension or direct linking, which I think would be > inappropriate. While there are good cases for (third party) extending a KOS (eg > by including local extensions), the wording in the intro to section 3 is perhaps > a little enthusiastic and might run the risk of not sufficiently recognizing the > potential problems of linking two different KOS. LIS experience has recognised > that any major KOS represents a particular world view and that joining two > different KOS in an effective manner is not necessarily straight forward. Hence > the emphasis on distinct mapping relationships. > > Perhaps the editorial team could consider the appropriate order of the linking > and mapping sections, whether more discussion on the rationale for mapping could > be included, and whether some more guidance might be given on when to link and > when to map. > > The linking example in section 3.1 brings up a currently somewhat problematic issue. > > A new concept scheme can re-use existing concepts using the skos:inScheme > property. Consider the example below, where a reference concept scheme for > animals defines a concept for "cats": > > > However there is nothing to prevent a new developer attaching their own new > concept to someone else's existing SKOS scheme and thus changing the scheme (if > the links are followed). It would be bad practice but as far as I understand is > possible. (A slight modification of the example in 3.1 illustrates the point below.) > > I appreciate this is integral to the open world model and in the long run, it > might be addressed by mechanisms of assigning provenance to RDF (sets of) > statements, development of trusted vocabulary registries, caution when importing > a SKOS vocabulary, etc. In the near future, I believe that the majority of > applications will be effectively closed world, in that they will create an > in-house index or database based on selected resources from the Web (including > linked data publications). Perhaps the SKOS primer might also address more > immediate concerns of how a vocabulary provider might make their vocabulary > available. Is it possible to say something on how KOS developers might publish a > vocabulary in SKOS, while asserting some practical form of ownership? > > Apdx > > Eg A slight modification of the example in 3.1 if I understand it correctly > ============= alt example (undesirable?) > ex1:referenceAnimalScheme rdf:type skos:ConceptScheme; > dc:title "Reference list of animals"@en. > ex1:cats rdf:type skos:Concept; > skos:prefLabel "cats"@en; > skos:inScheme ex1:referenceAnimalScheme. > > The creator of another concept scheme devoted to cat descriptions can freely > include the reference ex2:abyssinian concept in AN EXISTING scheme, and then > reference it as follows: > > ex2:catScheme rdf:type skos:ConceptScheme; > dc:title "The Complete Cat Thesaurus"@en. > > ex1:cats skos:inScheme ex2:catScheme. > > ex2:abyssinian rdf:type skos:Concept; > skos:prefLabel "Abyssinian Cats"@en; > skos:broader ex1:cats; > skos:inScheme ex1:referenceAnimalScheme. > > > > >
Received on Friday, 17 October 2008 08:15:20 UTC