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

Mon Sep 8 18:13:45 PDT 2003

Rich:

First and foremost many thanks for putting together the measurements
and units ontologies!

Shawn and I had a look at it today. It looks very good to me!
I've discussed today with Shawn also a number of "SMS services" (no,
not the short messaging system ones ;-) that we can provide on top of:

1. generic semistructured graphs (RDF)
2. the SEEK unit and measurements ontologies
3. generic OWL ontologies.

For example (1) would include general graph operations as well as some 
logic views such as class(C), property(P), etc.

(2) will include functions/predicates to do automatic unit conversion, 
compatibility checking (e.g. list all units compatible with a given
dimension) etc 

(3) we may want to add reasoning services such as subsumption. For
example we may want to test  C1 => C2 (every C1 is also a C2) and then 
construct a hierarchy based on concept subsumption

We also need to combine in a suitable way, the semantic types given by 
ontologies with the programming languages types eg a la Haskell. 

Bertram

>>>>> "RW" == Rich Williams <rwilliams at nceas.ucsb.edu> writes:
RW> 
RW> Replies are interspersed below
RW> Rich
RW> 
>> -----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).
>> 
RW> 
RW> The classes that end in "Concepts" could indeed go away.  I created them as
RW> an organizational convenience.  They basically top level containers designed
RW> to make browsing the ontologies easier, an issue especially when the
RW> ontology gets large.
RW> 
>> Is ReferenceValue something specific to your Food Web
>> application? I don't
>> really understand what a referenced value signifies.
>> 
RW> 
RW> It's not used yet, I put it in as a place holder that can get developed in
RW> the future.  It's meant to be a pointer of some kind to a data value, to be
RW> used for example when data values are stored in a separate file.  So if the
RW> data was in an XML file it could be a file name and an xpath location path.
RW> There's a lot of work to do here - for example, data are typically in data
RW> sets that consist of one or more files, and there's no need to redundantly
RW> store file names in every data reference.
RW> 
>> 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?
>> 
RW> 
RW> Your confusion is due to some confusing terminology.  RatioMeasurement is
RW> 'ratio' in the sense of nominal-ordinal-interval-ratio used by statisticians
RW> and described I believe in the eml-attribute documentation.  It does not
RW> mean that the measurement is a ratio of two quantities (though it could be).
RW> Ratio in that sense, as well as densities, concentrations etc would all be
RW> represented using the Dimension, which is defined in the Unit (note that
RW> IntervalMeasurement has a Unit property that is inherited by the
RW> RatioMeasurement class).
RW> 
>> It seems like Precision and Accuracy need to be related to a Measurement?
>> 
RW> 
RW> I think that the correct relationship is that precision and accuracy are
RW> properties of NumericValues.  It's not in there yet though...
RW> 
>> 
>> Shawn
>> 
>> 
>> >
>> > Rich
>> >
>> 
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RW> 
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