Introducing Astro MOAT - can we add semantic knowledge to tags using the IVOA vocabuaries?
dburke at cfa.harvard.edu
Tue Sep 30 08:52:26 PDT 2008
Q: Where can Astro MOAT be found?
This is currently re-directed to my poor little home machine so access
may be slow.
Q: What is a MOAT?
A: Quoting from the MOAT (Meaning Of A Tag) site , "MOAT (Meaning Of
A Tag) provides a Semantic Web framework to publish
semantically-annotated content from free-tagging".
It is basically a list of tags with associated URIs, which provide the
"semantic meaning(s)" of the tags, and a simple way to access this
information from a server.
Q: Well, what on earth is an Astro MOAT then?
I took the SKOS versions of the IVOA thesaurus and A&A keywords and
turned the fragments of the URIs into tags - so  creates a tag called
"galactic". I repeated the process for the UMD astronomical ontology
, although I didn't convert all URIs from this ontology, and added a
few tags based on some external resources, such as UMBEL , OpenCyc
, and DBPedia . I have also used the contents of the preferred and
alternate labels for the SKOS documents to create tags.
I don't know if this counts as "use of a specification" in terms of
maturity of an IVOA document :-)
Q: How about an example?
A: The tag agn can be accessed via
to see the HTML version (which has been enhanced with links built from
the SKOS ontology) and the information in N3 format - which looks like
@prefix : <http://moat-project.org/ns#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
<http://purl.org/net/djburke/demo/astromoat/tag/agn> a :Tag ;
:name "agn" ;
:hasMeaning [ a :Meaning ;
foaf:maker <http://purl.org/net/who/djburke> ] .
It is the latter information that is the basis of the MOAT server; the
additions I've made to the HTML output are just experiments in seeing
whether the semantic structure in the vocabularies can help users to
select useful tags (as are the exceedingly-simple search options I've
Q: Are all the tag really useful?
A: Probably not; some of the labels in the vocabularies result in tags
that are on the ungainly side of the spectrum - such as
"astronomicalinstrumentationmethodsandtechniques" - or that would likely
never be used - e.g. "unitlessnumberof" - but there presence doesn't
really hinder the process.
Q: How is it used?
A: At the moment this is a piece of "build it and they will (hopefully)
come" semantic middle-ware. I am playing around with it to tag some
resources (e.g. chandra press releases, registry records) to see whether
you actually do add useful knowledge by this process, but I'd love to
hear if other people find a use for it.
Q: How could it be used?
A: The "classic" example for a MOAT client is as a part of a blogging
application, which can then list possible URIs for a user-supplied tag.
You could imaging something like this being done for institutions
writing press releases, or anyone writing an astronomy blog.
However, it is much-more interesting (and useful) to suggest tags given
some "resource" (I'm thinking of things like abstracts for telescope
proposals or registry resources), but this is a bit more of an
open-ended effort. It'll be interesting to see what happens with
projects like  ("Linking Open Data Tagging System") and 
("SemanticProxy.com from the Calais team").
Q: Can anyone add a meaning for a tag?
A: The MOAT specs do allow users to add new tags, or add meanings to
existing tags, but I currently don't support this. I could do, if it
became a useful service.
Let me know if you have any questions or comments,
Doug Burke | http://hea-www.harvard.edu/~dburke/
Harvard-Smithsonian | Email: dburke at cfa.harvard.edu
Center for Astrophysics | Phone: (617) 496 7853
60 Garden Street MS-2 | Fax: (617) 495 7356
Cambridge, MA 02138 | Office: B-440
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