- From: Ed Summers <ehs@pobox.com>
- Date: Tue, 19 Aug 2008 01:59:21 -0400
- To: "SWD WG" <public-swd-wg@w3.org>
Whoops, I meant to say owl:intersectionOf instead of owl:unionOf in several parts of my last email. My apologies for the confusion. //Ed On Tue, Aug 19, 2008 at 1:00 AM, Ed Summers <ehs@pobox.com> wrote: > I took an action at the last face to face to offer up some text > describing why ISSUE-40 Concept Coordination was postponed. > > http://www.w3.org/2008/04/22-swd-minutes.html#action02 > > It's been a busy summer, and a long time coming, but here it is. If > you have the energy please give it a read over to make sure that 1) I > characterize the difference between pre and post-coordination > correctly; 2) the alternatives including ex:coordinationOf, > owl:unionOf and SPARQL are sound ; and that 3) I captured the spirit > of this decision appropriately. > > //Ed > > 4.4 Coordinating Concepts > > Indexing practices involving thesauri and other KOS often include the > notion of coordination. Coordination is an activity in which concepts > from a KOS are combined together. In general there are two kinds of > coordination: pre-coordination [1] and post-coordination [2]. The key > distinction between the two hinges on when the actual coordination > occurs in relation to an information retrieval event. > > Pre-coordination is done prior to information retrieval, by a KOS > maintainer, or by an indexer who is using a KOS. For example, if a > concept scheme includes a concept for "Bicycle Repair" it is > considered to be pre-coordinated concept of the concept "Bicycle" and > "Repair". In addition it is also considered to be pre-coordination > when an indexer takes two existing concepts from a concept scheme, > like "Bicycles" and "Repairing", and combines them with a given syntax > like "Bicycles--Repairing" to index a particular document. > > Post-coordination on the other hand is performed as part of an > information retrieval task. For example if a given document is indexed > with two distinct concepts "Bicycles" and "Repairing" and a user > decides to perform a search for all documents that are indexed with > "Bicycles" and "Repairing". > > SKOS has some facilities for representing concept coordination. The > most basic form of pre-coordination is certainly expressible with > SKOS: > > ex:bicycleRepair a skos:Concept ; > skos:prefLabel "Bicycle Repair"@en . > > Post-coordination as an information retrieval activity also lends > itself to representation as a SPARQL query. For example, given two > distinct concepts: > > ex:bicycles a skos:Concept ; > skos:prefLabel "Bicycles"@en . > > ex:repairing a skos:Concept ; > skos:prefLabel "Repairing"@en . > > you could construct a SPARQL query to return only the documents that > are indexed with both concepts: > > SELECT ?document > WHERE { > ?document dc:subject ex:bicycles . > ?document dc:subject ex:repairing . > } > > However the SKOS vocabulary itself does not provide any mechanism for > expressing that a given concept consists of a pre-coordination of > other concepts. Of course it is perfectly feasible to extend SKOS [3] > to establish a pattern for representing coordinated concepts. For > example it has been suggested [4] that a new property such as > <code>ex:coordinationOf</code> could be established: > > ex:coordinationOf a rdf:Property ; > rdfs:domain skos:Concept ; > rdfs:range rdf:List . > > Which could then be used in assertions such as: > > ex:bicyclesRepairing a skos:Concept ; > ex:coordinationOf (ex:bicycles, ex:repairing) ; > skos:prefLabel "Bicycles--Repairing"@en . > > It has also been suggested that OWL itself could be used to coordinate concepts: > > ex:bicyclesRepairing a skos:Concept ; > owl:unionOf (ex:bicycles, ex:repairing) ; > skos:prefLabel "Bicycles--Repairing"@en. > > However, established patterns for pre-coordinations of this kind have > not yet emerged in the SKOS community. <code>ex:coordinationOf</code> > (or some equivalent extension), and the ramifications of using SKOS > with OWL [5] have not been explored fully enough yet to warrant > inclusion in the SKOS Reference [6], and consequently in this Primer. > Rather than commit to a design pattern that hasn't been proven useful, > the Semantic Web Deployment Group decided to postpone the issue of > coordination [7], to allow extension patterns to organically emerge as > SKOS is deployed. The hope is that as successful patterns are > established they can be documented as a W3C Note or some equivalent. > @@ TODO include info about wiki/discussion list here or in > Specialization section? @@ > > [1] http://www.willpowerinfo.co.uk/glossary.htm#pre-coord > [2] http://www.willpowerinfo.co.uk/glossary.htm#post-coord > [3] http://www.w3.org/TR/skos-primer/#secskosspecialization > [4] http://isegserv.itd.rl.ac.uk/public/skos/press/dc2006/coordination.html > [5] http://www.w3.org/TR/skos-primer/#secskosowl > [6] http://www.w3.org/TR/skos-reference/ > [7] http://www.w3.org/2006/07/SWD/track/issues/40 >
Received on Tuesday, 19 August 2008 05:59:58 UTC