A plehtora of Quantities

[Guy Rixon]

On Thu, 13 May 2004, Ed Shaya wrote:

>
> >I understand the concept and the starting point.  I just don't see a case for
> >defining a new 'type' that all things must derive from. I can see a case for
> >a 'Measure' but even that is a bit high.  For example, are there any
> >programming languages that define such things?  No - they give you the
> >components to assemble your own structures, because building root types like
> >this hinder later.
> >
> >
> I don't think of quantity as a root type.  Ontologically there are
> objects (Things) and quantities (properties).  Observation is a Thing
> not a property, an SED is a property.

Yes, but by the time we get to operate on it, the property "SED" has been
reified into "Measurement of SED recorded in a data structure" and
we're modelling the latter.  I don't think we touch properties in the
ontological sense.

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