Describing things for software to read

[Martin Hill]

On Wednesday 13 August 2003 4:20 pm, Roy Williams wrote:
> >  As far as I can
> > tell, all efforts so far to define a dictionary of complete and unique
> > terms have failed because it's very difficult.
>
> Or maybe impossible? Can we really imagine defining science words in such a
> close and accurate way that they can be compared by a computer, yet the
> community of astronomers will agree to it? Does the word "planet" include
> Pluto? What exactly does the word "image" mean?

Even if it's impossible we still need to do it :-) otherwise we will not be 
able to do the joins and comparisons that we want to, nor carry out the kind 
of automatic registry searches that we intend to.  We don't have to define 
all words; we 'just' have to define terms that describe certain data values 
that apply to the astronomy world.  (I see possible cause of confusion: 
'Complete' here meant that the term(s) must describe the value completely, 
rather than all things must be described).  Certainly we must be careful 
about trying to find a Universal Solution that is so generic and vague that 
it is very difficult to use in practice.

The data modelling team are working on describing data values, which is 
useful for data servers.  This forum probably needs to look at (if it's not 
done already!) how it will describe metadata in the registry using terms that 
software can interpret.  How, for example, will we say that a particular data 
set contains intensities in absolute ergs, while another contains the same 
information but in magnitudes?  Similarly with passband filters, pixel 
resolutions, data quality, etc, etc. 

-- 
Martin Hill
Astrogrid/AVO, ROE
Tel: 07901 55 24 66