- From: Aldo Gangemi <aldo.gangemi@istc.cnr.it>
- Date: Fri, 04 Nov 2005 18:53:01 +0100
- To: Dan Brickley <danbri@w3.org>, public-swbp-wg@w3.org
- Message-id: <p06210207bf914845fc5e@[10.42.6.98]>
At 11:10 -0500 4-11-2005, Dan Brickley wrote: >I don't know the best URI to cite, but >http://www.schemaweb.info/schema/SchemaInfo.aspx?id=62 >...has a handy overview of the Wine Ontology. I think it >would be very interesting to try a SKOS representation of this, >to explore how a thesaurus (eg. faceted) approach looks. > >Dan My idea at the discussion was that the semantics of a node label is similar to a complete definition of an owl class, e.g. in the wine ontology: http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#WhiteWine intersection of: http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#Wine restriction: on property: http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#hasColor has value: http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#White which just says that a wine:WhiteWine is a wine that wine:hasColor wine:White. In a thesaurus, this would be represented as WhiteWine being an NT of Wine, eventually having an RT semantic relation to Color, or even to White. Of course in thesauri, no constraint is given on the semantics of NT or RT. Now suppose that that wine thesaurus wants to introduce a node label for "wines-by-color", which would be a "collection" having as "member" WhiteWine, in your current solution for node labels. But if we go back to owl, the semantics of the wine-by-color node label would be most likely the following: http://xxxxxxxxxxxxxxxxx/wineThes#WineByColor intersection of: http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#Wine restriction: on property: http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#hasColor cardinality: 1 i.e. that a wine-by-color is a wine that has a cardinality=1 on the property hasColor. A DL reasoner will easily infer that WhiteWine is a subClassOf WineByColor. So far for the semantic issue. And that's why I dislike the disjointness between concepts and collections in SKOS. As far as the pragmatic issue is concerned, i.e. that node labels are not used for annotating, it can be solved in several ways (I suggest to add an annotation property to a node-label-derived class), but not within object-level OWL(DL), and motivately so: usage of metadata should not be part of their set-theoretic semantics. On the other hand, SKOS domain is not similar to the Wine domain: it is about concepts, not wines, then one may claim that the usage of metadata concerns exactly the semantics of concepts. And here we are back to the same alternative found in th WN TF: are thesaurus (wordnet) concepts (synsets) to be treated as instances, or migrated to classes? SKOS does the same as the WN datamodel in OWL, and treats concepts as instances. Therefore, we may be tempted to do something weird to node-label-derived instances. What I suggest is not btw to make a partition concepts/collections, but to introduce a new property that allows "node-label" assertions to some instances of the "concept" class, e.g.: Class(Concept partial restriction(hasNodeLabel allValuesFrom(xsd:boolean))) Individual(WineByColor type(Concept) value(hasNodeLabel, T)) and eventually introduce a special subClass for node labels: Class(NodeLabel complete intersectionOf Concept restriction(hasNodeLabel oneOf(T))) If the problem is that thesauri experts refuse to call node labels "concepts", just create a more general class, e.g. "descriptor", and make both concepts and node labels subclasses of it: Class(NodeLabel complete intersectionOf Descriptor restriction(hasNodeLabel oneOf(T))) Class(Concept complete intersectionOf Descriptor restriction(hasNodeLabel oneOf(F))) Ciao Aldo -- Aldo Gangemi Research Scientist Laboratory for Applied Ontology Institute for Cognitive Sciences and Technology National Research Council (ISTC-CNR) Via Nomentana 56, 00161, Roma, Italy Tel: +390644161535 Fax: +390644161513 aldo.gangemi@istc.cnr.it http://www.istc.cnr.it/createhtml.php?nbr=71
Received on Friday, 4 November 2005 22:25:31 UTC