- From: Richard Cyganiak <richard@cyganiak.de>
- Date: Fri, 30 Jan 2009 15:04:14 +0000
- To: Peter Ansell <ansell.peter@gmail.com>
- Cc: Michael Hausenblas <michael.hausenblas@deri.org>, Linked Data community <public-lod@w3.org>, Semantic Web community <semantic-web@w3.org>
Peter, On 29 Jan 2009, at 23:11, Peter Ansell wrote: > What was the rationale behind having both void:target and the > combination of void:subjectsTarget and void:objectsTarget? > > I would have thought that linksets would always be directed, otherwise > it leaves you uncertain about whether you can actually find anything > in one set or the triples are actually contained in the other dataset. > At least with subjectsTarget you can always be sure that that dataset > will contain the relevant triples. Reiterating what others said: Containment of link triples in a dataset, and direction of the link statements, are two separate issues. Containment (which dataset physically contains the triples, that is, where can I find them via resolving URIs or via SPARQL queries or dumps) is indicated via void:subset. The linkset is a subset of the dataset that contains the link triples. Directionality of the statements (which dataset provides the subjects, and which the objects?) is an orthogonal question. Note that dataset A could contain links to B of the shape "a:foo dc:creator b:bar" or of the shape "b:bar dc:creator a:foo". SubjectsTarget and objectsTarget can be used to distinguish between them. The superproperty void:target was included for cases where we want to specify less about the linkset. For example, I might just want to express the general fact that A contains links to B, without saying anything about what predicate is used or what the subjects and objects are. Hope that explains things. Best, Richard > If people use two void:target > statements as part of a linkset can we only assume that they are > trying to include triples from both datasets at once? If so, the > target's might contain anything resembling the statistics that one > might be able to apply to directed linksets where one is really only > trying to describe a subset of triples from void:subjectsTarget that > happen to have object resources in another known dataset? > > Cheers, > > Peter >
Received on Friday, 30 January 2009 15:05:00 UTC