[seek-kr] RE: Please tear this apart...

[Rich Williams]

Replies are interspersed below

Rich

> -----Original Message-----
> From: seek-kr-admin at ecoinformatics.org
> [mailto:seek-kr-admin at ecoinformatics.org]On Behalf Of Shawn Bowers
> Sent: Monday, September 08, 2003 11:46 AM
> To: seek-kr at ecoinformatics.org
> Subject: [seek-kr] RE: Please tear this apart...
>
>
> On Mon, 8 Sep 2003, Rich Williams wrote:
>
> >
> > Of course the units ontology I wrote is only a small piece of
> what you are
> > asking about, but none the less, I think it is an ontology by
> most common
> > computer science definitions and is quite similar to the units
> ontology that
> > you posted.  (Of course this begs the question of what is the difference
> > between an ontology and a database schema - in general, my
> answer is 'not
> > much'...  See for example p156 in Sowa's Knowledge Representation book)
> >
> > I've checked in a slightly revised version of it, and also a
> new figure that
> > includes the slot relationships that hopefully makes its
> structure clearer
> > (I omitted them in the original for clarity).  I also isolated
> my attempt at
> > describing measurements from its extension to ecological measurements in
> > particular and called the ontology MeasurementBase.  It's in the same
> > seek/projects/kr/ontologies folder as the Units ontology.  It
> includes the
> > units ontology, and so gives a picture of how units relate to
> measurements
> > etc.  There's a figure, MeasurementBase.gif, of the ontology.
>
> I actually downloaded the ontology into Protege, and used
> Graphviz to view
> it :)
>
> I think it looks great.  I only have a few suggestions/questions...
>
> It seems like the classes that end in "Concepts" are really meta classes
> (and could probably go away). For example, Measurement and Measurement
> Context are particular Measurement Concepts. In other words, if I have an
> instance of a Measurement (e.g., 5 g/cm), it probably shouldn't be an
> instance of a Measurement Concept too (which is assumed by the IS-A).
>

The classes that end in "Concepts" could indeed go away.  I created them as
an organizational convenience.  They basically top level containers designed
to make browsing the ontologies easier, an issue especially when the
ontology gets large.

> Is ReferenceValue something specific to your Food Web
> application? I don't
> really understand what a referenced value signifies.
>

It's not used yet, I put it in as a place holder that can get developed in
the future.  It's meant to be a pointer of some kind to a data value, to be
used for example when data values are stored in a separate file.  So if the
data was in an XML file it could be a file name and an xpath location path.
There's a lot of work to do here - for example, data are typically in data
sets that consist of one or more files, and there's no need to redundantly
store file names in every data reference.

> It looks like you included RatioMeasurement as an IntervalMeasurement. It
> seems like it should have a property that further defines its units... or
> that it is created from two measurements?  How would Proportions and
> Densities/Concentrations be represented?
>

Your confusion is due to some confusing terminology.  RatioMeasurement is
'ratio' in the sense of nominal-ordinal-interval-ratio used by statisticians
and described I believe in the eml-attribute documentation.  It does not
mean that the measurement is a ratio of two quantities (though it could be).
Ratio in that sense, as well as densities, concentrations etc would all be
represented using the Dimension, which is defined in the Unit (note that
IntervalMeasurement has a Unit property that is inherited by the
RatioMeasurement class).

> It seems like Precision and Accuracy need to be related to a Measurement?
>

I think that the correct relationship is that precision and accuracy are
properties of NumericValues.  It's not in there yet though...

>
> Shawn
>
>
> >
> > Rich
> >
>
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