- From: Nathan <nathan@webr3.org>
- Date: Mon, 04 Oct 2010 15:05:22 +0100
- To: Bernard Vatant <bernard.vatant@mondeca.com>
- CC: Pat Hayes <phayes@ihmc.us>, Semantic Web <semantic-web@w3.org>
Bernard Vatant wrote: > Hello Nathan, Pat > > 2010/10/4 Nathan <nathan@webr3.org> > >> Pat Hayes wrote: >> >>> Well, the very idea of a *blank* node is one that has no name, so this >>> idea seems to be rather against the spirit of the bnode, so to speak. Of >>> course, concrete syntaxes do use bnode identifiers, but these are really >>> just an artifact of the need to represent a graph in a linear character >>> sequence. These bnode identifiers are purely local to the graph. >>> >> Hmm, does this mean then that often people are using blank nodes as if they >> have a name, and should this be avoided? >> >> for example: >> >> _:x1 rdf:type ex:Person ; rdfs:label "Nathan"@en . >> :Bob :knows _:x1 . >> :Sue :knows _:x1 . >> >> as far as I know many RDF processors (and indeed common understanding) >> would treat this as if to say that: "The person that Bob knows called Nathan >> is the same person that Sue knows called Nathan" >> > > Indeed it's the way I've ever understood it myself. And actually it's the > kind of use I often present in introducing bnodes, with even less > description of the object, not even a label. > Just to say that :Bob and :Sue have some common relation, about whom I don't > know anything whatsoever otherwise. > > :Bob foaf:knows _:x1 . > :Sue foaf:knows _:x1 . > > Can I (question for Pat, here) declare this in abstract syntax, without > bnode identifiers? Or should I go through some convoluted declaration of > non-empty class? > > >> When it appears that correct interpretation would be "Bob knows a person >> call Nathan and Sue knows a person called Nathan" >> > > Well, my (maybe naive ) assumption was that using the same bnode identifier > was making for the same-ness of the resource. That's my worry, is it asserting the sameness or not? if i swap out bnodes for "something" then Bob knows something that is a Person with a label of "Nathan" Sue knows something that is a Person with a label of "Nathan" but I don't see any sameness. Perhaps I could reverse the question to ask, if I parsed the following graph: _:x1 rdf:type ex:Person ; rdfs:label "Nathan"@en . :Bob :knows _:x1 . :Sue :knows _:x1 . Could I then serialize it as: :Bob :knows [ rdf:type ex:Person ; rdfs:label "Nathan"@en ] . :Sue :knows [ rdf:type ex:Person ; rdfs:label "Nathan"@en ] . or _:g1 rdf:type ex:Person ; rdfs:label "Nathan"@en . :Bob :knows _:g1 . _:g6 rdf:type ex:Person ; rdfs:label "Nathan"@en . :Sue :knows _:g6 . If the answer is yes, then there is no sameness I guess. Best, Nathan
Received on Monday, 4 October 2010 14:12:49 UTC