Taxonomic hierarchy in SDD

Eric Zurcher Eric.Zurcher at PI.CSIRO.AU
Thu Nov 29 15:06:15 CET 2001

At 12:38 PM 28-11-01 +1100, Kevin Thiele wrote:

>Concerning Steve's exemplar drawn from a DELTA butterfly treatment: I've
>added a few challenges to the challenge cases (number 9 in the attached)
>specifically designed to address representation of DELTA datasets in the new
>standard. Personally, I don't think we should start with a DELTA data set as
>our first challenge, for several reasons:
>1. We have agreed several times that it's important not to be canalized by
>DELTA or any other existing representation, but to keep the existing
>representations in mind while working. Starting with XDELTA seems to me to
>increase the risk of canalization

While canalization is a risk, there certainly is also merit in trying to
retain the best features of "prior art". The DELTA format has persisted for
over 20 years, which is nearly an eternity in the IT field. It must have
been doing one or two things right. There's no need to follow it too
closely, but certainly we can learn quite a bit from DELTA about what works
well and what doesn't.

>2. Of all the descriptions in the world, 99.9999999% of them are not in
>DELTA. Probably 99.999% of them are textual (natural language) descriptions.
>Surely this should form the basis of our first challenge, methinks.

I think that's actually a rather harsh assessment of DELTA's uptake. Let's
say there are about 4x10^6 known species. We'd like descriptions for them
all, along with descriptions of higher taxonomic levels (genera, families).
So the magnitude of total number of descriptions is about 10^7. I'd guess
that the number of taxa with DELTA descriptions is of the magnitude of
10^5. So that means roughly 1% of all taxa already have a DELTA description.

>3. Related to 2 above, many (though by no means all) DELTA datasets are
>already abstractions from the source (a set of natural language
>descriptions). We should start with the source.

The source? Surely the ultimate source is observations made on individual
specimens. If we wish to start with the source, the first thing that needs
to be done is to make sure that we have a system which can adequately
describe a specimen in hand.

(Sorry if I get too defensive about DELTA. I just can't help myself...)

Eric Zurcher
CSIRO Livestock Industries
Canberra, ACT Australia
E-mail: Eric.Zurcher at

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