Protégé as SKOS editor
Dr Nicolas Figay, HDR shared Combined usage of SKOS
and OWL: an experimentation on the Digital Europa Thesaurus,
which among others addresses the visualization of semantic graphs. The
report includes: Experimentation Step 2: opening a SKOS thesaurus with
Protégé with import of SKOS RDF Schema for OWL DL. I had difficulties
in obtaining the same outcome as reported and by 24. March 2023 added a
comment on this. Dialogue with colleague Volkan Çağdaş,
volkan@yildiz.edu.tr, provided a solution. The outcome is presented
below.
Use of Protégé as SKOS editor
Start Protégé. Via File / Open open your SKOS file.
Via the Classes tab you should see among others
skos:Concept, and
Via the Entities tab you should see the many
Individuals of skos:Concept
Back to the Active ontology tab.
The lower third of the window presents a sub-window
with title Imported
ontologies.
The relevant ontology is rendered by the file
‘skos-owl1-dl.rdf’ ,
which may be imported directly from
http://www.w3.org/TR/skos-reference/skos-owl1-dl.rdf. Alternatively,
the file may be downloaded and stored locally, before it is imported
(to reduce transfer time during import).
The imported file should now be mentioned among
Imported ontologies.
Via File/Save save and integrate the files. - Do note that the
integration implies that the saved file includes both a link to the
imported file/ ontology, but also a re-arrangement of the namespaces
above. The original SKOS .rdf files should thus be kept in a different
folder, or strict naming rules applied.
Via the ObjectProperty tab notice the rich hierarchy
of semantic
relations.
Via Windows / Views / Individual views / Annotations
you get access to
the content of the SKOS file and can start editing.
The file you saved includes as mentioned above both the
imported file/ ontology, but also a re-arrangement of the namespaces.
Most likely it is stored with a .rdf extension. You may change the
extension from .rdf to .owl (e.g. when you save the file first time).
Then (next day) when you start Protégé and open the
.owl file, you should be able to
to start editing right away. But do be concerned to navigate between
the .owl compliant and the .rdf compliant version of your SKOS file.
Visualization of SKOS broader and narrower relations,
etc. by means of Protégé and OntoGraf
Start Protégé. Via File / Open open your SKOS file, import
‘skos-owl1-dl.rdf’, and save (if it is not done already).
Via Windows / Tabs / (List of tabs) make sure that OntoGraf is marked
Click the OntoGraf tab. When the window opens, in the Search entry,
write the name of an Individual and click the Search button. A number
of concept relations should appear in various colors. In the line below
the Search entry and button, find and click the ArcTypes button.
If the number of ArcTypes is only two, go to File /
Open . You are
asked whether you want to open in the current window. Respond: No, and
select the file that you just stored.
Again find Windows / Tabs /
OntoGraf . Click OntoGraf and repeat the search – or search another
Individual.
Now you should be able to edit the depiction of
semantic relations
among the Individuals.
In the default setting, clicking the Search button presents Individuals
which
‘contains’ the searched concept. Additionally, from the field to the
right of the Search entry, you may select other options (starts with,
ends
with, exact match, regexp) to get other related Individuals.
Again, if your SKOS file is saved with .owl extension, you should be
able to go directly to OntoGraf and visual
editing.
Erik Stubkjær, est@plan.aau.dk, 2023-05-22.