VOEvent vocabulary?

[Alasdair Gray]

On 7 Jun 2008, at 19:46, Frederic Hessman wrote:

> Glad to hear the Trieste meeting was so successful and that the list  
> of things to do looks interesting.  Rob gave me the task of  
> preparing a VOEvent vocabulary, a job I'm happy to assume with your  
> help.
>
> For those of you who haven't read the proposed vocabulary standards  
> document, here's the executive summary:
>
> 	- the format for vocabularies is the W3C SKOS/RDF standard,  
> expressed either in XML or in "Turtle" (a short form without all of  
> the <tags>);

Just a wee minor correction. At Trieste it was decided that a  
vocabulary must be published in rdf/xml and should also be published  
in rdf/turtle.

Alasdair

> 	- vocabularies basically consist of some number of entries each  
> having:
> 		- a simple token for computers (e.g. "grb");
> 		- simple labels for humans (e.g. "gamma-ray burst"), potentially  
> localized to different languages;
> 		- optional aliases;
> 		- optional links to other entries which are related, broader or  
> narrower concepts;
> 		- optional misc documentation (e.g. descriptions, usage hints,...)
> 	- vocabularies can be easily "mixed and matched" so that no  
> vocabulary has to be totally self-contained and complete;
> 	- no one has to use anyone else's vocabulary - there's nothing like  
> a universal must-use vocabulary like UCD1 - and indeed, the  
> expectation is that each community will create, maintain, and  
> publish their own specialized vocabularies (an unusually democratic  
> idea with the VO);
> 	- you're asked to publish a translation between your vocabulary and  
> some other (hopefully more standarized) vocabulary;
> 	- the IVOA is expected to provide a centralized collection of  
> vocabularies (or copies thereof) and their translation tables.
>
> Presently, the draft standard has several examples of vocabularies  
> which can now be used "right out of the box":
> 	- an IAU constellation vocabulary mainly used as a simple example  
> but useful already to keep track of Cygnus, Cygni, ...
> 	- the ancient but august IAU 1993 taxonomy (we don't have to come  
> up with a token for an armillary sphere, IAU93 already has one) all  
> in caps but with translations into French, German, Italian, and  
> Spanish;
> 	- a version of the A&A thesaurus keywords;
> 	- the AVM (formerly AOIM) taxonomy used by the outreach community;
> 	- a SKOS version of UCD1, not (yet) intended to be the standard  
> document, but which encapulates the present standard in a non-text  
> based, computer-processible format.
>
> In addition, I've been preparing a draft IVOA thesaurus ("IVOAT")  
> which cleans up the IAU93 vocabulary - errors removed, labels not  
> just in caps, updated with new concepts.  Since I've promised the  
> semantics group to finish a working draft of IVOAT fairly soon, the  
> simplest (and undoubtedly best) solution is to do exactly that and  
> then use VOEvent - again - as the leading edge example of why a  
> controlled vocabulary is needed and how it's used.
>
> If you want to browse some vocabularies, try my ad hoc collection at
> 	Proposed IAU/IVOA Thesauri in SKOS Format
> or, even better, try Alaisdair Gray's "Vocabulary Explorer", where  
> you can select different vocabularies, search for terms, and follow  
> the related/narrow/broader links:
> 	Vocabulary Explorer
> For example, go to the above link and input the search term "grb":  
> you will get links to an IVOAT and an A&A vocabulary reference and  
> you can follow the respective ontological links.
>
> VOEvent needs a controlled vocabulary (indeed VOEvent is used as one  
> of the best examples in the semantics document).   There are two  
> options:
>
> #1 : use IVOAT
>
> The downside of IVOAT is that it's large - so VOEvent developers  
> must know that most of it won't be needed.
> The upside of IVOAT is that it's large - so VOEvent developers will  
> be able to trust that most of the words they might need to use/parse  
> will be in it.
>
> #2: create a unique VOEvent vocabulary
>
> Such a process is certainly within the intent of the Vocabulary  
> standard - may a thousand vocabularies bloom.   I think that -  
> practically - this is not worth the effort right now given that any  
> additions needed by VOEvent could just as easily be the final  
> additions/corrections to IVOAT before it becomes a standard (of  
> sorts).  On the long term, however, the VOEvent will probably want  
> to maintain an additional vocabulary for new tokens which can't be  
> added easily, quickly, or unbureaucratically into an IVOA standard.
>
> You might think that - given this - the best solution is to go ahead  
> and create a longer VOEvent vocabulary and ignore IVOAT.     
> Fortunately, the VOEvent community is sufficiently broad that this  
> job would be much more work than to simply use IVOAT at first - no  
> work needed - and then prepare for the situation that VOEvent will  
> eventually need an additional specialized vocabulary (or not).
>
> Thus, my suggestion to all of you interested in vocabularies for  
> VOEvent is:
> 	- assume that VOEvent at first uses IVOAT, which should take care  
> of 98% of our needs at first with practically no work;
> 	- gear up to access this and other vocabularies, assuming that they  
> will be hosted centrally at IVOA;
> 	- decide whether your own VOEvent software wants to read XML or  
> Turtle (both should be available for correctly published  
> vocabularies);
> 	- see if you can find any terms you'd like to use but can't find in  
> the present IVOAT standard;
> 	- start collecting specialized terms for a small VOEvent vocabulary.
>
> I'd be happy to hear your opinions.
>
> Rick
>

Dr Alasdair J. G. Gray
agray at dcs.gla.ac.uk
http://www.dcs.gla.ac.uk/~agray



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