SV: do we need it?

[Tony Linde]

> The point of the draft under discussion is not to include all possible
> astronomical terms in the SV, but to be able to express any possible
> astronomical term, locally defined, in terms of standard SV tokens (or

That is what I assumed - good news.

It'd still be good to get some use cases defined. We've heard from Bernard
that the vocabulary and ontology will satisfy quite different needs. It'd be
good to know that we are developing the SV for the right reasons - and if
the use cases indicate an equally pressing need for an ontology(ies), we can
raise the priority of that activity.

One further question: some of the foregoing discussion indicated that there
might be other vocabularies beside the SV - is that right? What would these
be used for and what terms, other than what is in the SV, would they
include?

T.

> -----Original Message-----
> From: Andrea Preite Martinez [mailto:andrea.preitemartinez at iasf-
> roma.inaf.it]
> Sent: 18 September 2007 16:46
> To: Tony Linde
> Cc: semantics at ivoa.net
> Subject: RE: SV: do we need it?
> 
> Quoting Tony Linde <Tony.Linde at leicester.ac.uk>:
> 
> > I'm wondering what astronomical terms would not be included in the
> SV?
> >
> The point of the draft under discussion is not to include all possible
> astronomical terms in the SV, but to be able to express any possible
> astronomical term, locally defined, in terms of standard SV tokens (or
> words, as we call them in UCD-ish).
> 
> Example 1. You are a data provider publishing in the VO your data on
> the optical V-band magnitudes of your sources. You locally call them
> v-mag. But v-mag is your dialect, so you register your data as
> providing phot.mag;em.opt.V, which is the standard VO way of saying
> optical magnitude in the V band.
> Now, phot.mag;em.opt.V is an UCD, and UCDs are a VO standard that tell
> people how to form UCDs using the standard, maintained, list if
> UCD-words (or UCD-tokens!!). So, you are expressing your concept (your
> quantity) not looking for the UCD-equivalent of optical V-band
> magnitude in a list of UCDs (which does not exist!) but you are
> expressing your concept in terms of the standard UCD-words, in this
> example:  phot.mag and em.opt.V .
> 
> Example 2: suppose you want to register (I take the example of
> registering your data, just because this is the first step to move
> from local to VO-wide) your data on circumstellar matter around B
> stars. This is the sort of metadata information that you cannot
> express in terms of UCDs. We were not yet done with UCDs that we (all)
> realized the need to overcome this problem.
> Is circumstellar matter around B stars an astronomical concept? Yes.
> Can you find it in the SV? No. The SV tells you how to combine the
> list of SV tokens in order to get something like:
> diffuse;location.circumstellar;star.spectralType.B
> 
> Ex. 3: Or you can publish an alert on a GRB, using in the "what" (I
> suppose) field  the SV equivalence
> time.variation.burst;ucd:em.gamma
> (note here the use of the namespace ucd: to mark that em.gamma is a
> token in the UCD-words list) in order to be sure to be understood in
> the VO compliant community.
> 
> This approach is by far more flexible and practical than standardizing
> a list of all possible astronomical terms. I say so by personal
> experience. Last year I spent many weeks of tedious skimming through
> the way astronomers generate neologisms in astronomy. Take a look at
> Table 5 of the Note at
> http://ivoa.net/Documents/latest/AstroKeysTN.html .
> 
> There you can find a shortened list of well semantically defined
> terms, that are used by astronomers to mint a large variety of
> semantically different terms (or sub-terms, but this is not the point
> for the moment). And this is only the floating part of the iceberg! I
> also tested for variations around the term x-ray: I found more that
> 700 different terms. I cannot tell you how many SV+UCD tokens would be
> necessary to express these 700 concepts, but I'll be happy to pay a
> round in Edinburgh if they were more than a few ten! We'll find a
> reason to drink anyway!
> 
> This said, I think the discussion going on (in particular on vocab
> formats) is extremely important, because the draft addresses the
> problem only at the, let?s say, the default, or minimal, level.
> Being able to define higher levels could take us to a fascinating land
> indeed!
> 
> Andrea
> 
> 
> 
> 
> =======================================================================
> ============
> Andrea Preite Martinez                 andrea.preitemartinez at iasf-
> roma.inaf.it
> IASF                                   Tel.IASF:+39.06.4993.4641
> Via del Fosso del Cavaliere 100        Tel.CDS :+33.3.90242452
> I-00133 Roma                           Cell.   :+39.320.43.15.383
>                                         Skype   :andrea.preite.martinez
> =======================================================================
> ============
>