[From Bruce Abbott (941202.2000 EST)]
Some while back I posted ECOLI6a, a version of my nutrient-regulating e. coli
that included Bill Powers's FramePlt graph plotting routine to make visible
the changes in dNut and nutrient levels ("fuel") over time. I never heard a
word from anyone about this--did anyone try it? Last week I gave a copy of
the program to my brother, who did run it and came back with an interesting
comment I thought I'd share with CSG-L. He thought that the graph of dNut
over time looked suspiciously like chaos. I agree. In fact, I think it would
look even more "regular" (if that term can be applied meaningfully to a
chaotic process) if the simulation environment were simplified to include only
one, rather than the current two, nutrient sources. Anyone care to comment?
By the way, according to Bill's definition, this one "learns" too: the high-
level "fuel" regulating system alters the gain of the lower-level dNut control
system. (I still disagree that this is learning.)
I've been under the weather for a few days and so have gotten behind in my
correspondence. I have a few comments I'd like to make about Hans Blom's post
on learning and modeling and Bill's reply to it, but that will have to wait
until the morrow. And I haven't forgotten about the operant project, either.
I agree with Bill that our strategy should be to focus on terminal performance
first and worry about learning later, as appears necessary.
Cheers,
Bruce