Confused

[Guy Rixon]

Tony,

perhaps it's an implementation dispute rather than a definition thing?

The IVOA data models are now specified to be expressible using UML.  That is,
they only contain relationships "is a" and "has a" (and perhaps "owns" if we
distinguish composition from aggregation).  The ontological content is
restricted, so much of this modelling can be done with existing tools that
support OOA.

Conversely, if we use lots of relationships, then we have to use specialised
tools from recent ontology research; tools that look vaporous right now.

I think your definitions are right.  I also think that many VO folk ignore the
ontological theory behind their current modelling because it's not necesary to
know the thory to use the technique.

On Fri, 8 Nov 2002, Tony Linde wrote:

> I've seen comments saying that we should use metadata instead of
> ontologies, data models instead of ontologies, data models instead of
> metadata etc.
>
> So what is the difference? And what do people mean by these terms?
>
> For myself:
>
> Data is information stored electronically.
> Metadata is data which describes some other data.
> Dataset is a collection of data organised by some principle.
> Data model is an ERM of a dataset which describes its underlying
> construction.
>
> Ontology is all of the terms and semantic relationships used in some
> domain discourse (which may be discovered and stored digitally but not
> necessarily).
>
> How about you?
>
> Cheers,
> Tony.
>
> __
> Tony Linde                       Phone:  +44 (0)116 223 1292
> AstroGrid Project Manager        Fax:    +44 (0)116 252 3311
> Dept of Physics & Astronomy      Mobile: +44 (0)7753 603356
> University of Leicester          Email:  ael at star.le.ac.uk
> Leicester, UK   LE1 7RH          Web:    http://www.astrogrid.org
>
>
>

Guy Rixon 				        gtr at ast.cam.ac.uk
Institute of Astronomy   	                Tel: +44-1223-337542
Madingley Road, Cambridge, UK, CB3 0HA		Fax: +44-1223-337523