Dichotomy

[Mr Fortuner connection modem]

Rigidity of Delta: I was thinking of the way the characters are defined, this
cumbersome coding in particular, which looks as simple as an English zip code
! Also the fact that Delta does only dichotomy and that the way the data is
coded doesn't seem to make it usable by other methods. Now, this may change
with the new CONFOR. I'll be interested to see the way it stores metadata.


You say : By `dichotomous' I presume you mean `deterministic' or
`non-probabilistic'.
No, not really, because any identification system IS
probabilistic. What you call deterministic would be a probabilistic system
with a 100% probability.

Identification is always a probabilistic process.
Unless you are a pompous egotistic fool, you can never be 100% sure that you
have correctly identified a species. (In the previous sentence, the word
"never" should be taken with a probability of 95.4% as there are cases when
you ARE 100% sure, e.g., when you identify H.sapiens sapiens Q although there
are times when I wonder). I prefer a similarity program which tells me that
the unknown is 100% similar to species A and 99% similar to species B to a key
which tells me that it IS species A (with species B 50 lines below).

No, by
dichotomous key I mean a key which works by dichotomy (in logic, dividing a
class into 2 opposed subclasses), a key which asks me if the flowers are red
or white, and too bad if my specimen is pink or if my population includes 75%
red flowers and 25% white ones (Mendel was there).

I hate dichotomous keys
since high school, when I had to use "La flore complete de la France, de la
Suisse et de la Belgique". The survey on identification methods will show if
others are feeling the same way. So far only 3 answers. I wish the silent
majority will speak up.

Renaud Fortuner
fortuner at math.u-bordeaux.fr