IVOA Thesaurus

[Alasdair Gray]

Hi Rick,

 

I have just been analysing your IVOA Thesaurus. (The version I have used
is Wed Oct 24 15:25:24 2007.)

 

First of all I would like to talk about top level concepts. I found that
there were 2,646 top level concepts. I feel this very high, particularly
as there are only about 2,850 concepts in total. This is also
particularly bothersome if you analyse the IAU Thesaurus which only has
516 top level concepts.

 

>From this I have a question for everyone, how many top level concepts
does it make sense to have?

 

My opinion about top level concepts is that they should aid the user to
explore the vocabulary. As such, I believe that there should be only a
limited number of top level concepts that can be easily displayed at one
time, e.g. at most 50 but probably significantly less.

 

In going through the concepts that appear at top level concepts, I can
see plenty of terms that appear as top level concepts that I would think
are narrower than other terms, e.g. I would think that telescope
mountings should be a narrower term than telescope. Likewise for the
many other concepts to do with different features of telescopes.

 

 

 

My second issue is to do with maintenance. In going through the
vocabulary I have found quite a few errors that have crept in due to the
editing process. (The list can be found at the bottom of this email.)
Some of these are simple typos but others are where identifiers have
been changed for a concept and the subsequent edits have not been made
for all of the relationships involving that edit. Others make the
vocabulary poly-hierarchy inconsistent, e.g. acceleration of gravity has
gravity as a broader term but the inverse relation is not present in
gravity. I think that we need to develop scripts that can check that the
inverses of all of the relationships that are declared in the hierarchy
are present. This would be based on the related relationship being
symmetrical and the broader/narrower being inverses of each other.

 

I hope this all helps. Rick, please keep up the good work on generating
the IVOA thesaurus.

 

Alasdair

 

Errors that I have identified in the thesaurus:

 

The following are labels that I believe appear as identifiers in a
relationship but have not been defined as concepts in their own right.
This is probably due to typos or the changing of identifier labels.

  faberjacksondistances

  ugeminoriumstars

  ubvrijklphotometry

  light

  differentialimagemotionmonitor

  neutralhydrogen

  yerkesgalaxyclassification

  tsubdwarfstars

  blackdwarfs

  correlations

  Igalaxies

  cgalaxies

  millimeterwaves

  Isubdwarfstars

  bose0einsteinnuclei

  period0colorrelations

  rareearths

  whitedwarfs

  tullyfisherrelations

  seconarymirrors

  oortsconstants

  kuiperbelt

  lineofsight

  multislitspectraphs

  multifiberspectraphs

  cosmologicalparameters

  seti

 

 

Alasdair J G Gray <http://www.dcs.gla.ac.uk/~agray/> 

Research Associate: Explicator Project

Computer Science, University of Glasgow

0141 330 6292

 

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