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Re: [SMW-devel] Units in RDF
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From: Markus <ma...@ai...> - 2006-05-10 13:14:22
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On Wednesday 10 May 2006 12:46, Denny Vrandecic wrote: > Hi Mov, > > I'm afraid that MathML's unit support seems not compatible with RDF > (blame the W3C for that --- I hope I am wrong). At least the snippet you > send doesn't look like valid RDF. > > The RDF Primer contains a solution for units, though, which could be > followed: > > http://www.w3.org/TR/2004/REC-rdf-primer-20040210/#rdfvalue > > I would rather oppose the other way -- using an XML literal instead --- > because of it's "out-of-RDF"-semantics. Yes, we should stay compatible with RDF. But the solution from the primer=20 doesn't strike me as too brilliant either. First of all it uses blank nodes= =20 in vain, which is not recommended. Secondly, it puts the relevant informati= on=20 one level deeper into the graph, which might affect query efficiency.=20 =46or complx structures, there is no other way, but I would prefer to keep = the=20 graphs simple as long as this is feasible. In the way that we currently use= =20 units only to rename attributes, one basically looses all unit information.= =20 But so far no use case requires us to know more about the unit than whether= =20 it is the same for two values of one property or not. If more elaborate uni= t=20 information would be needed, I would opt to append it to the declaration of= =20 the *attribute* (with the unit). Do one obtains=20 attribute:Elevation_above_sea_level-23km smw:has_Unit_Factor swi:Meter attribute:Elevation_above_sea_level-23km smw:has_Unit_Scale 10^3^^xsd:deci= mal or something similar. Should be as queryable as the other version, but has = the=20 advantage that it is RDF with the most important data, the attributes value= ,=20 still being in place. And we avoid dublicating unit information every time = a=20 value is given to some attribute. =2D- Markus > > best, > denny > > MovGP0 wrote: > > We had a lot discussion about how to format Units within the > > Articlesource, how to present them to the user, and how to store it > > within the database. But what I'm missing so far is the discussion how = to > > express Numerical Values within RDF. Currently each Entry without a > > fitting Type looks like: > > > > <snip/> > > > > <smw:Thing rdf:about=3D"http://wiki.ontoworld.org/index.php/_San_Die= go"> > > <attribute:Elevation_above_sea_level-23m > > rdf:datatype=3D"http://www.w3.org/2001/XMLSchema#decimal">12.8</attribu= te:E > >lev ation_above_sea_level-23m> > > </smw:Thing> > > > > <owl:DatatypeProperty > > rdf:about=3D"http://wiki.ontoworld.org/index.php/_Attribute-3AElevation= _abo > >ve_ sea_level-23m"> > > <smw:hasArticle > > rdf:resource=3D"http://wiki.ontoworld.org/index.php/Attribute:Elevation= _abo > >ve_ sea_level"/> > > <rdfs:isDefinedBy > > rdf:resource=3D"http://wiki.ontoworld.org/index.php/Special:ExportRDF/A= ttri > >but e:Elevation_above_sea_level"/> > > </owl:DatatypeProperty> > > > > <snap/> > > > > What I'm missing here is the unit, because you might better write it as > > MathML: > > > > <smw:Thing rdf:about=3D"http://wiki.ontoworld.org/index.php/_San_Diego"> > > <attribute:Elevation_above_sea_level> > > <math:apply> > > <math:times/> > > <math:cn math:type=3D"float">12.8</math:cn> > > <math:csymbol > > math:definitionURL=3D"http://wiki.ontoworld.org/index.php/Meter">m</mat= h:cs > >ymb ol> > > </math:apply> > > </attribute:Elevation_above_sea_level> > > </smw:Thing> > > > > See also: http://www.w3.org/TR/mathml-units/ > > > > Ys, MovGP0 > > > > > > > > ------------------------------------------------------- > > Using Tomcat but need to do more? Need to support web services, securit= y? > > Get stuff done quickly with pre-integrated technology to make your job > > easier Download IBM WebSphere Application Server v.1.0.1 based on Apache > > Geronimo > > http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=3D120709&bid=3D263057&dat= =3D121642 > > _______________________________________________ > > Semediawiki-devel mailing list > > Sem...@li... > > https://lists.sourceforge.net/lists/listinfo/semediawiki-devel > > ------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job > easier Download IBM WebSphere Application Server v.1.0.1 based on Apache > Geronimo > http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=3D120709&bid=3D263057&dat= =3D121642 > _______________________________________________ > Semediawiki-devel mailing list > Sem...@li... > https://lists.sourceforge.net/lists/listinfo/semediawiki-devel =2D-=20 Markus Kr=F6tzsch Institute AIFB, University of Karlsruhe, D-76128 Karlsruhe ma...@ai... phone +49 (0)721 608 7362 www.aifb.uni-karlsruhe.de/WBS/ fax +49 (0)721 693 717 |