- From: Bernard Vatant <bernard.vatant@mondeca.com>
- Date: Tue, 31 Oct 2006 10:32:35 +0100
- To: Semantic Web <semantic-web@w3.org>, Marc <marc@geonames.org>
A use case for linked data ... Trying to connect Geonames "features" in France with geographical entities published by INSEE last summer. I have e.g. for the region "Bretagne" the respective URIs http://sws.geonames.org/3030293/ and http://rdf.insee.fr/geo/REG_53 What should be the recommended practice if the declarations are made from Geonames side, in files published in Geonames namespace, and not necessarily endorsed by INSEE? The least commitment is http://sws.geonames.org/3030293/ rdfs:seeAlso http://rdf.insee.fr/geo/REG_53 It does not implies any actual semantic identification of Bretagne as defined by Geonames and Bretagne as defined by INSEE. Any interpretation is possible. The commitment is too weak if I want to say that both resources defined the same thing, somehow. A higher level of commitment is to declare from Geonames side that INSEE data are authoritative, so one would think about the following http://sws.geonames.org/3030293/ rdfs:isDefinedBy http://rdf.insee.fr/geo/REG_53 But actually this is wrong, since the INSEE resource does not define at all the Geonames resource. After that, the only choice seems to be http://sws.geonames.org/3030293/ owl:sameAs http://rdf.insee.fr/geo/REG_53 This is a very strong commitment indeed. It means all assertions made on one resource hold for the other. It means I have checked and will continue to check that what is declared on Geonames side is consistent with what is declared on INSEE side. And moreover, since owl:sameAs is symmetrical, it adds semantics to INSEE resources that they have not endorsed and may disagree with. So it seems we have the choice between something too weak, open to any interpretation, and something too strong. I have proposed at some point [1], but this proposal seems to have met so far a polite refusal from the community, to use something in-between by indirecly linking the two resources to the same blank node, using dc:subject. It's stronger than rdfs:seeAlso, and weaker than owl:sameAs. http://sws.geonames.org/3030293/ dc:subject _:b http://rdf.insee.fr/geo/REG_53 dc:subject _:b The idea behind this is that neither Geonames resource nor INSEE resource are definitive or exhaustive. They provide two identifiers and two descriptions of the same subject, but this declaration says that this subject is not "definitely defined" by any of those resources, which might be in their current state inconsistent or out of sync, and then are not technically the same in the sense of owl:sameAs. Moreover, this mechanism allows to aggregate other, non-RDF resources http://en.wikipedia.org/wiki/Bretagne dc:subject _:b Of course if that seems a weird hacking of dc:subject, some other property could be proposed. But I think the SW needs something of the like anyway. [1] http://universimmedia.blogspot.com/2006/04/identifying-things-blank-nodes-again.html -- *Bernard Vatant *Knowledge Engineering ---------------------------------------------------- *Mondeca** *3, cité Nollez 75018 Paris France Web: www.mondeca.com <http://www.mondeca.com> ---------------------------------------------------- Tel: +33 (0) 871 488 459 Mail: bernard.vatant@mondeca.com <mailto:bernard.vatant@mondeca.com> Blog: Leçons de Choses <http://mondeca.wordpress.com/>
Received on Tuesday, 31 October 2006 09:32:42 UTC