Hi Michael,
Michael Hausenblas wrote:
Francois,
Thanks for your feedback and the question. Though I'm not sure what you
technically mean with 'my:links is a named graph' :)
The system output the links in a named graph. See the following example
in TRiG:
<my:links>
{
<http://kmi.open.ac.uk/fusion/dblp#document1632795751_264>
owl:same_as
<http://kmi.open.ac.uk/fusion/dblp#document1ad8378bff1fe32cd13989741b50fe3eaef0db93>
.
}
We can then describe it as a void:Linkset as I've described below. This
allows to attach other information such as the author of the linkset,
the parameters of the algorithm used to generate it, etc.
I think the answer
is simple: indeed we decided to model datasets and linksets
independently from each other. The following example from the (not yet
publicly available) voiD guide may illustrate this:
Let's assume the two well-known linked datasets DBpedia and DBLP:
:DBpedia void:containsLinks :DBpedia2DBLP .
:DBpedia2DBLP rdf:type void:Linkset ;
void:target :DBLP .
So, it is a linking *from* DBpedia *to* DBLP; as RDF is a direct graph,
this makes sense quite a lot (the subject 'sits' in DBpedia, the object
in DBLP).
IIRC, we had your option in mind as well [1] but decided to go for the
current modeling due to the above reasons. Actually, as I think, the two
modelings are equivalent, just with reversed directions:
YOUR model (if I got it right):
:dataset1 <- void:target - :links - void:target - > :dataset2
Right.
voiD model:
:dataset1 - void:containsLinks -> :links - void:target - > :dataset2
There's quite a difference between the two models. In the actual voiD
model it is supposed that the links are included in one of the datasets.
This approach raises again the owl:same_as related problems of stating
logical equivalence of resources as part of the dataset itself.
Experience in ontology alignment shows that it's wiser to consider the
linkset as a separate entity pointing to both (or more) datasets. This
also allows to have more than one linkset for a given pair of datasets
(why not, I can trust one linkset more than the other...). Finding links
from a dataset is done by querying on void:Linkset objects pointing to
this dataset. Actually, this approach is followed by the oddLinker of
LinkedMDB, a linkset being recorded as a oddlinker:linkage_run entity.
Cheers,
Francois
Cheers,
Michael
[1] http://community.linkeddata.org/MediaWiki/index.php?MetaLOD#Discussion
----------------------------------------------------------
Dr. Michael Hausenblas
DERI - Digital Enterprise Research Institute
National University of Ireland, Lower Dangan,
Galway, Ireland
tel. +353 91 495730
http://sw-app.org
----------------------------------------------------------
François Scharffe wrote:
Hi Michael,
thank you for the link ;)
It seems that the current voiD spec supposes that the linkset (set of
interlinks) is supposed to be included in one of the two interlinked
datasets. I think it would make sense for the linkset to be considered
independently from the two interlinked datasets, something like this:
my:links a void:Linkset ;
void:target <dataset1> ;
void:target <dataset2> ;
my:links is a named graph containing the set of owl:same_as links.
This would avoiD to bind a dataset with a set of links.
Cheers,
François
Michael Hausenblas wrote:
Just to let you know. One of the outcomes of the recent VoCamps [1]
was that we have agreed on a final layout for voiD (Vocabulary of
Interlinked Datasets). It is now available at [2] - please note that
the actual (final) namespace will be 'http://rdfs.org/ns/void#' ...
can't fix everything within two days, right :)
A more detailed user guide to follow soon!
Cheers,
Michael
PS: A big thanks to the Neologism (http://neologism.deri.ie/) people
for creating such an awesome tool and John Breslin for the great
support re rdfs.org!
[1] http://vocamp.org/wiki/VoCampGalway2008#Outcomes
[2] http://rdfs.org/ns/neologism/void
----------------------------------------------------------
Dr. Michael Hausenblas
DERI - Digital Enterprise Research Institute
National University of Ireland, Lower Dangan,
Galway, Ireland
----------------------------------------------------------
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