UCD and DM

[Ed Shaya]

Roy Williams wrote:

>Brian and Ed,
>
>  
>
>>>>Our
>>>>view is that the UCD are concepts that will inherit (as a class)
>>>>from the quantities
>>>>        
>>>>
>
>In the UCD group we are considering a model based on triples: [Concept,
>Property, Value]. Each part of the original tree can now play a role in one
>of the triples. For example, in the sentence "My apple weighs 400g", we have
>a Concept (apple), and an instance of the Concept (My apple), then the
>property (weight), and the value (400g).
>
>(1) Ed's model has some overlap here. For example, the value part (400g) is
>an instance of "quantity". The units and data types makes a good fit here.
>
>(2) However, I do not understand what is meant by "VO_Class". Is this the
>class of the Concept (Apple), or is it about the property (Weight)?
>  
>
The master plan is to have all of the astronomical Concepts  (UCDs?)  
under  VO_Class.  Having put Quantity under VO_Class, it automatically 
puts all of the observables under it as well since they will inherit 
from Quantity.
Independently we need to put astronomical objects and datacenter objects 
under VO_Class starting with top level objects Universe, dataCollection, 
and dataSet and then galaxy, star, ISM, table etc.  One benefit of this 
is that a common set of metadata is easily applied.  I put name, 
description, id, and idRef as a start of such metadata that one wants 
for all AstronomyThings.
What is neat about RDF/OWL is that it acts like a schema and one can 
create XML instance documents
immediately (if you don't mind the triplet way of doing things).  I make 
apple a roy:Thing and weight a VO:Class
and voila:

<roy:apple rdf:ID="MyApple" VO:name="MyApple" VO:Id="Saturdays">
        <VO:description>The one on my table since last 
Saturday.</VO:description>
        <VO:hasProperty>
            <VO:weight rdf:ID="MyAppleWeight" VO:NumberOfValueElements="1">
                <VO:hasUnits rdf:resource="&VO;#g"/>
                <VO:hasValues>
                         <VO:ValueList VO:datum="400"/>
                 </VO:hasValues>
          </VO:weight>
        </VO:hasProperty>
</roy:apple>

>(3) Both DM and UCD groups are interested in what types of quantities (or
>values as we call them) can be used for what types of properties? In other
>words, if I say "My apple weighs {0.1, 0.3, -0.4}km/sec", how can a formal
>system figure out that this is wrong?
>  
>
As I explained to Sebastien,  Weight would inherit from ScalarQuantity 
or can simply be a ScalarQuantity by  setting the range of its hasFormat 
property to DataFormat rather than AbstractFormat or TupleFormat.
One can also create a massUnit Class and have the gram instance of 
that.  Weight could be restricted to only
hasUnits of VO:massUnit.  Most Ontology editors would then tell you 
immediatly that the above is a no-no.
That is, if you want to do your validation via OWL.  I am not sure yet 
that is the best way, but it is quite interesting that one could 
theoretically do schema creation, document creation and validation 
within the OWL/RDF environment AND it is considerably easier than XML 
Schema.

>Roy
>
>  
>