Markus et al, what you are saying is true. However... the RDF Working Group that is currently in operation will, hopefully, come up with a proposed syntax (probably based on TriG) and, more importantly, some sort of a semantics for named graphs, hopefully in alignment with SPARQL. I cannot say, of course, when this will be finalized and how it will align with the timing of the Wikidata project. But it is worth knowing about it and, actually, possibly to keep an eye on it and contact the WG if the (obviously important!) Wikidata use case does not align with what the WG is doing.
(And, of course, I am happy to do the go-between when and if the time comes:-) Cheers Ivan On Apr 6, 2012, at 17:31 , Markus Krötzsch wrote: > Martynas, > > what you are proposing below is not W3C recommended RDF but an extension of > triples to quads. As far as I know, this extension is not compatible yet with > existing standards such as SPARQL and OWL. Named graphs work with SPARQL, but > are mostly used in another way than you suggest. Most RDF database tools > would be *very* unhappy to get millions of named graphs in combination with > queries that use variables as graph names. The syntax you use is not a W3C > standard either. > > This does not say that N-Quads aren't a good idea if one can get them to work > with the rest of the Semantic Web stack, but it really defeats your own > arguments. We are committed to supporting *existing* standards (as we have > said many times already), but we will not base our software design on a > non-standard RDF-variant that works with neither OWL nor SPARQL. > > Markus > > > On 06/04/12 13:09, Martynas Jusevicius wrote: >> Hey Denny, >> >> I gave it a shot: >> >> <http://dbpedia.org/resource/France> >> <http://dbpedia.org/ontology/PopulatedPlace/populationDensity> >> "116"^^<http://dbpedia.org/datatype/inhabitantsPerSquareKilometre> >> <http://wikidata.org/graphs/France2012> . >> <http://dbpedia.org/resource/France> >> <http://dbpedia.org/ontology/populationDensity> >> "116"^^<http://www.w3.org/2001/XMLSchema#double> >> <http://wikidata.org/graphs/France2012> . >> >> <http://wikidata.org/graphs/France2012> >> <http://purl.org/dc/terms/date> >> "2012"^^<http://www.w3.org/2001/XMLSchema#year> >> <http://wikidata.org/graphs/France2012> . >> <http://wikidata.org/graphs/France2012> >> <http://purl.org/dc/terms/source> _:source >> <http://wikidata.org/graphs/France2012> . >> _:source<http://purl.org/dc/terms/published> >> "2010"^^<http://www.w3.org/2001/XMLSchema#year> >> <http://wikidata.org/graphs/France2012> . >> _:source<http://purl.org/dc/terms/title> "Bilan demographique"@fr >> <http://wikidata.org/graphs/France2012> . >> >> The syntax is N-Quads. It does not use reification, but instead named >> graphs for provenance. The necessary concepts were already present in >> DBPedia. >> >> As you might know, temporal provenance is not the strongest point of >> RDF. However conventions and solutions are available, and I am sure >> implementing them would require far less effort than creating a custom >> data model from scratch, not to mention the benefits of potential >> reuse. >> There's quite some research done on RDF provenance, which is worth >> looking into if provenance is really a key feature for Wikidata from >> day one. I see it as something that should work transparently behind >> the scenes, and therefore could be rolled-out later on. >> >> You would get much better and more extensive advice than mine on >> [email protected] -- the only prerequisite is willingness to >> cooperate. >> >> RDF's strength is that it solves data integration problems by pivotal >> conversion, reducing the number of model transformations from >> quadratic to linear: >> http://en.wikipedia.org/wiki/Data_conversion#Pivotal_conversion >> A custom data model brings up questions which already have an answer >> in the Semantic Web stack: >> # can data from different Wikidata instances be merged or interlinked >> natively? >> # is there a native query language? In case of SQL, how performant >> will it be given many JOINs and the planned use of provenance? >> # what and how many custom serialization formats and API mechanisms >> will have to follow? >> >> Stacking one custom solution on top of another can eventually result >> in huge costs. I honestly think the energy of Wikidata could be >> directed in a more productive way. >> >> >> Martynas >> graphity.org >> >> >> 2012/4/5 Denny Vrandečić<[email protected]>: >>> Dear Martynas, >>> >>> if you try to model the following statement in RDF >>> >>> "The population density of France, as of an 2012 estimate, is 116 per square >>> kilometer, according to the "Bilan demographique 2010"." >>> >>> you might notice that RDF requires a reification of the statement. The data >>> model that you have seen provides us with an abstract and concise way to >>> talk about these reifications (i.e. via the statement model, just as in >>> RDF). >>> >>> We still have not finished the document describing how to map our data model >>> to OWL/RDF, but we have thought about this the whole time while discussing >>> the data model. >>> >>> But if you find a simpler, and more RDFish way to express the above >>> statement, please feel free to enlighten me. I would be indeed very >>> interested. >>> >>> Cheers, >>> Denny >>> >>> >>> >>> 2012/4/5 Martynas Jusevicius<[email protected]> >>>> >>>> it doesn't look like reuse of existing concepts and standards is a >>>> priority for this project. >>>> One cannot build a Semantic Web application by ignoring its main >>>> building block, which is the RDF data model. >>> >>> >>> -- >>> Project director Wikidata >>> Wikimedia Deutschland e.V. | Eisenacher Straße 2 | 10777 Berlin >>> Tel. +49-30-219 158 26-0 | http://wikimedia.de >>> >>> Wikimedia Deutschland - Gesellschaft zur Förderung Freien Wissens e.V. >>> Eingetragen im Vereinsregister des Amtsgerichts Berlin-Charlottenburg unter >>> der Nummer 23855 B. Als gemeinnützig anerkannt durch das Finanzamt für >>> Körperschaften I Berlin, Steuernummer 27/681/51985. >>> >>> >>> _______________________________________________ >>> Wikidata-l mailing list >>> [email protected] >>> https://lists.wikimedia.org/mailman/listinfo/wikidata-l >>> >> >> _______________________________________________ >> Wikidata-l mailing list >> [email protected] >> https://lists.wikimedia.org/mailman/listinfo/wikidata-l > > > _______________________________________________ > Wikidata-l mailing list > [email protected] > https://lists.wikimedia.org/mailman/listinfo/wikidata-l ---- Ivan Herman, W3C Semantic Web Activity Lead Home: http://www.w3.org/People/Ivan/ mobile: +31-641044153 FOAF: http://www.ivan-herman.net/foaf.rdf
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