Roy, hello.
On 2008 Feb 4, at 22:10, Roy Williams wrote:
> But I am still waiting for the cost benefit analysis.
Hang on: you asked for use-cases, you got use-cases. You want a cost- benefit analysis?
> I know very little about it except that precision of expression is
> possible (eg "I want Supernovae Ia but not Ic").
Precision (neigher too much nor too little) is the goal here.
> I worry that there are many vocabularies with no agreement.
The goal is multiple vocabularies, with just the right amount of agreement.
> I worry that there are many representation technologies for
> vocabularies that use complicated languages.
Nope, just SKOS.
I'm taking it that the application of all this to VOEvent will be to have very slightly magic strings in the 'why' position. There are some finicky technicalities about the best way to curate, version and distribute these, and these are what are being discussed on the semantics list. But these technicalities are all about how one makes vocabularies robust no-brainers for the users, with the first representative of 'the users' being the VOEvent standard authors, and the subsequent developers who will use their standard.
> I worry that use of vocabularies will require knowledge of complex
> matters like namespaces,
Barely.
> schema extension,
Yuk. No!
> sparql,
If you want to do funky things with VOEvents or archives of them, then it might turn out that this would help, but it won't be necessary.
> skos
Perhaps a very little.
> rdf,
Nope.
> owl,
Definitely not (heh, unless you're Brian!)
> I worry about no being able to use SQL or even Xquery but must learn
> a new query language.
_In principle_ there's a slight complication in that the namespace prefixes (why='voevent:supernova1a') are arbitrary (this is the same issue that the Registry folk had to handle a few months ago). But if you want to, you could specify VOEvent to mandate that the prefix always be the same one (such as 'voevent:'), so the resulting string will be constant, and so you can SQL away all you like without ever having heard of SKOS. Of course, if you're restricting yourself to dumb string-matching, then you can't get the added value that supernova1a is a type of supernova.
> I worry that the creator of the VOEvent will also need to understand
> these complex technologies, meaning that few event streams will be
> done this way. Are any of these valid worries?
They are entirely valid worries. Fortunately, the answers to all of them are easy.
> (*) http://www.astronomerstelegram.org/
> click on "Post a New Telegram", you see these categories:
> Request for Observations, A Comment, AGN, Asteroids, Binaries, Black
> Holes, Comets, Cosmic Rays, Cataclysmic Variables, Globular
> Clusters, Gamma-Ray Bursts, Meteors, Microlensing Events, Neutron
> Stars, Novae, Planets, Planets (minor), Pulsars, Quasars, Soft Gamma-
> ray Repeaters, Solar System Objects, The Sun, Supernovae, Supernova
> Remnants, Transients, Variables, Stars
Delete the spaces, prefix a suitable URL and a '#' and bingo!, you've got your SKOS vocabulary. Job done! (attached)
Are you proposing this SKOS vocabulary for inclusion in the set of distributed vocabularies? I could sling it in the repository just now.
All the best,
Norman
-- Norman Gray : http://nxg.me.uk eurovotech.org : University of LeicesterReceived on 2008-02-05Z00:01:15
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