Re: Vocab AND Ontology?

From: Ed Shaya <eshaya-at-umd.edu>
Date: Wed, 10 Oct 2007 10:45:02 -0400

Rob Seaman wrote:
> On Oct 9, 2007, at 9:02 AM, Ed Shaya wrote:
> 

>> Found 2 biggies.  There is extended_sources but not:
>> sources
>>     point_sources alt unresolved_sources.

>
> We're losing ever more clarity. I thought this was to be a list of
> astronomical (i.e., physical) objects and processes, not any and all
> terms of empirical artifice. The same star may or may not be a point
> source, depending only on the technology and point of view.

It is a list of terms used by astronomers in astronomy and point_source is about as commonly used as they get (except for maybe "galaxy" and "star")

It is physical. It tells you about the sources physical size on images, which then can decide the process of analysis and photometric measurement. Indeed, the same Individual can indeed be classified in OWL as extended_source and point_source with no contradictions. So, you have given me an opportunity to talk about owl:disjointWith and owl:sameAs properties. When Instances of separate classes refer to the same Individual they can be identified with owl:sameAs to link them. If one is going to use point_source or extended_source it probably should be required to include information on either the image or the observatory used. For instance we could have:

astro:point_source id="IRAS1234+00" 

	instr:imagedBy instr:IRAS;
         misc:name "IRAS1234+00";
	phys:hasMeasurement astro:pt_flux3
	owl:sameAs id="Spitzer1234+00".

and

astro:extended_source id="Spitzer1234+00" 

	instr:imagedBy instr:Spitzer_IRAC"
         misc:name "IRAS1234+00";
	phys:hasMeasurement astro:extended_flux6;
	owl:sameAs id="Spitzer1234+00".

Now extended_flux may be a very different type than pt_flux, in that extended flux may provide the isophotal_radius or physical_radius or angular_radius of the flux included, while pt_flux would presumably be a total flux. Only extended_sources would have extended_fluxes allowed. Nevertheless this is the same astroObject and it is already indicated by having the same name, but the owl:sameAs tells OWL for sure.

Galaxy and Star probably should be declared owl:disjoint so that, even when the names are the same, if you try to declare a star and a galaxy to be sameAs, then it throws an error.

The point is that OWL can support the idea that the same Individual can be seen in different circumstances to be an entirely different animal.

Thanks,
Ed Received on 2007-10-10Z16:46:02